Effectively, this competition now expanded the existing Powergen Cup competition that had existed at the top end of the RFU’s Cup rugby pyramid; with the 2005–2006 Anglo-Welsh Cup the last time it would be sponsored by Powergen.

A revision in the format saw the twelve teams in the Guinness Premiership and the four Welsh regions drawn in a sixteen team competition with a four team pool format pitting each team against one of its pool rivals once during the course of the season making three pool matches for each club in total. One Welsh region to three English clubs made up the four pools; the winners of each of the four pools progressing to the semi-finals.

The pool stages were completed by December with the drawn semi-finals involving the four pool winners taking place as a semi-final double header in March at the Millennium Stadium followed by a grand final at Twickenham in April; the two Unions sharing their home grounds as venues for the showpiece occasions. 

There were no home and away fixtures as in the Heineken Cup and European Challenge Cup, but pools would retain the same four teams in the following season’s competition (2006-2007) reversing the home and away fixtures of the inaugural season, with the club relegated from the Guinness Premiership replaced by the club promoted to the Guinness Premiership from the English National Division One.

The Ospreys were drawn in Pool One alongside Bath, Bristol and Gloucester. Their first pool match was played at the start of October with the Welsh region travelling to Gloucester. The reigning Celtic League Champions suffered their first defeat in the competition at Kingsholm, a match in which the Guinness Premiership side overpowered the visitors to a 23-7 victory. Gloucester wing James Simpson-Daniel crossed the Ospreys' line within two minutes after woeful defending from the region. The Ospreys reduced the 10-0 deficit with a try from Steve Tandy in the second quarter but another penalty from Ludovic Mercier took Gloucester’s interval lead to 13-7. In a disappointing second half the Ospreys were unable to add any further points with the home side only adding a single penalty in thirty minutes of play after the resumption. Yet they were rewarded for constant pressure at the Ospreys’ line as Henry Paul secured a second try for the club ten minutes from time to seal the win.

In their second pool match, just eight days later, saw a second Ospreys defeat that ended their hopes in the Powergen Cup. Hosting Bath at home the Ospreys were awarded a penalty try in the first half, yet this was soon cancelled out due a score from Frikkie Welsh. The English side took the advantage into the break as Olly Barkley secured two penalties before the half-time whistle. The Welsh region took the lead in the second half thanks to a try scoring effort from Matthew Jones but a try from Bath’s Andy Williams, a drop goal from Chris Malone and two further penalties from Barkley secured the 20-27 win for the English side and set up a semi-final decider match with Gloucester eliminating the Ospreys from any further part in the competition in the process.

In the no-pressure game with Bristol Rugby in December the Ospreys put a 28-43 win over the English side in their own backyard. In a game in which both sides rested senior players, Marko Stanojevic secured a hat-trick for Bristol with Tommy Hayes impressive with the boot. An Ospreys brace from Adrian Cashmore plus additional tries from Damien Karauna, Steve Tandy and James Bater sealed the win as Shaun Connor provided the extras with his kicking. With only this win out of their three matches the Ospreys finished third in the Pool One and would meet the same three sides in the following year’s competition, in which they would hopefully improve on this performance.

Th prospect of Welsh advancement from Pool Two was also stopped in its tracks as the Cardiff Blues could only finish as runners up. The Blues were drawn against the London Wasps, London Irish and the Saracens, whom they met first at the Cardiff Arms Park in October. Craig Morgan attained the first Blues try which was swiftly followed by Jamie Robinson’s score, with his brother Nicky securing the conversion. Saracens could only manage a penalty in response but Robin Sowden-Taylor secured a third try for the home side. Kevin Sorrell achieved a try for the visitors as they headed 24-10 down into the interval. Matt Cairns took advantage of a depleted Blues side in the second half to score a try for the Saracens, yet when two of the visitors were sin-binned it was the Blues’ turn to take advantage as Nicky Robinson added the fourth try for a bonus point; he converted his own effort to take his personal haul to twenty-two points and to secure the victory for his side.

This successful start to the 2005–2006 Powergen Cup was marred less than a week later as the London Wasps entertained the Blues at the Causeway Stadium and secured a bonus point win over the Welsh visitors. Wasps took an unchallenged twenty point lead into the half-time break through tries from Ben Gotting and Ben Sackey. The Londoners dominated throughout, partly due to the Welsh region’s errors typified by the restart; Josh Lewsey charged down a Nicky Robinson attempted clearance to score underneath the posts. Two further penalties took the score to 33-0, effectively ending the match, but in an unexpected comeback the Blues notched up three tries courtesy of Chris Czekaj, Xavier Rush and Mama Molitika. Wasps had the last score of the game as James Brooks crossed late on for a bonus point-winning fourth try to close the scores at 40-19.

The Blues met London Irish at the Madejski Stadium retaining a slim hope of semi-final qualification. They took an early lead through a Nick Robinson penalty but Paul Gustard secured the first try for the home side. Despite another Robinson penalty a second Gustard try and another from Rodd Penney pushed London Irish into a commanding lead. Yet the Blues were kept in contention as Mike Phillips’s try reduced the home side’s advantage to 21-13 as the teams headed into the dressing rooms. A Gavin Williams try in the second period, plus conversion, reduced London Irish’s lead to just a point. A penalty apiece stretched the scores but the decisive score came for London Irish from a drop goal from Shane Geraghty, leaving the Blues second-placed in the table behind London Wasps and out of the competition.

The Dragons met Leicester Tigers, Worcester Warriors and the Northampton Saints in Pool Four of the Powergen Cup. The Welsh region rounded off September 2005 in fine fashion as they completed a superb win over the Tigers at a rain-soaked Rodney Parade. Craig Warlow secured the first Welsh score, after a break from Kevin Morgan, and although he missed the conversion on his own effort he eased the second conversion over after Ben Breeze had crossed the Leicester line. Shane Jennings clawed one back for the Tigers but the score at the interval remained in the Dragons’ favour at 18-10. Warlow continued to dominate the scoreboard in the second half as he attained a drop goal and another penalty with the Tigers only adding to their tally in the last ten minutes. Replacement Leon Lloyd crossed the line but as Ian Humphreys missed the subsequent conversion the Leicester Tigers missed out on a losing bonus point with the scores at the close of play 24-15.

In spite of their impressive first win in the competition the Dragons were overpowered by their next opponents, the Northampton Saints. Sean Lamont opened the scoring for Northampton after just six minutes and Jon Clarke secured the second try for the Saints ten minutes afterwards. Bruce Reihana stretched the lead to 18-0 before the half hour mark and the Saints remained unanswered in the remainder of the first half. Scrum half Mark Robinson added the third try of the match just a few minutes after the intermission. Reihana converted and added the fourth Northampton try of the game later into the half. Though Gareth Wyatt added a consolatory try for the Dragons late on, finalising the scores at 32-7, the bonus point win that the Saints had secured meant that the Dragons were unable to qualify for a semi-final position in the Powergen Cup.

The Dragons’ final Pool Four match saw them host the Worcester Warriors and gain a comfortable win over their visitors. The Welsh region attained an early lead through tries from Adam Black and Andrew Hall, leading 17-0 after the first quarter of the game. As the Dragons eased off the gas the Warriors replied with a superb try from Aisea Havili to reduce the home side’s advantage to 20-10 at the break. Worcester were unable to add to their tally in the second half as Warlow steadily increased his personal haul to eighteen points. The Dragons were awarded a penalty try in injury time after the Warriors illegally collapsed a scrum on their line, securing the 33-10 victory to end the competition on a high note.

The Scarlets entertained the Guinness Premiership’s Northern giants the Newcastle Falcons, Leeds Tykes and Sale Sharks in Pool Three. The Scarlets took an early six point lead over the Tykes in their first pool match thanks to the boot of Gareth Bowen. The home side’s defence yielded in the second half as Tal Selley secured a try in the fifty-third minute. The Scarlets ended the contest in the final quarter as they scored a brace of tries in four minutes from Iestyn Thomas and Matthew Watkins. Rob Rawlinson scored a consolatory try for the Tykes in the dying minutes of the game but it was too small an effort to dent the Scarlets' advantage as the final score remained 28-7.

The Newcastle Falcons travelled to Stradey Park for the second of the Scarlets' pool matches. Wales international Lee Byrne secured the first try of the game whilst replacement Jonny Wilkinson added a penalty soon after to reduce the deficit to a single point at 7-6. The England fly-half set up Anthony Elliott for a try soon after as the Falcons took the lead for the first time. Though Aled Gravelle squandered a chance for a try in reply, he secured a score just two minutes after his error to reduce the half-time deficit to just 12-13. Two minutes after the interval the Scarlets attained their third try of the game: Mike Hercus secured the score in the right corner and successfully converted his own effort. Wilkinson again set up a teammate to secure the second Newcastle try of the game as Tom May crossed the Scarlet line to once more secure an English lead. The Scarlets lost Inoke Afeaki to the sin bin but kept themselves in contention by not conceding further points. Gareth Bowen secured a long-range penalty with just five minutes of time remaining to secure the narrow 22-20 Scarlet victory and give the Welsh region a glimpse of a semi-final berth.

A scrappy encounter with Shale Sharks rounded off the Scarlets’ pool encounters. Despite an early Regan King try the Scarlets trailed 7-9 at the break. They pulled the lead back through a converted try from Hottie Louw with Mike Hercus stretching the lead to 17-9 with a penalty soon after. Welsh replacement Dwayne Peel entered the fray and spurred his team on, yet a yellow card for Simon Easterby let the English side back into the game. Two quick-in-succession converted Sale tries, from Chris Mayor and Elvis Seveali'i, reduced the Scarlets’ advantage to a single point, but the Welsh region bravely held onto their victory to secure a place in the semi-final to be played at the home of Welsh Rugby, the Millennium Stadium.

Bath progressed from the Ospreys’ pool to fill the semi-final berth against the Scarlets and in the second semi-final to be staged in Cardiff (London Wasps having previously disposed of Leicester Tigers in the earlier semi) an enthralling match between the Anglo-Welsh competitors brokeout.

Chris Malone secured two penalties for the English side but Craig Dunlea secured the first try of the game for the Scarlets with Mike Hercus slotting over the conversion. Bath began to govern the game as Alex Crockett secured his side’s first try, having been set up by former Scarlet Salesi Finau. Malone gained the conversion and added a penalty to extend the Bath lead to 16-7 at the half-time whistle. An early Hercus penalty on the restart reduced Bath’s advantage yet this was cancelled out due to a Joe Maddock five pointer to increase the deficit. The Scarlets maintained pressure which paid off as former All Black Regan King crossed the Bath line. When the English side were depleted due to a sin-binning winger, Mark Jones took advantage to secure another try for the Welsh region. Mike Hercus’s conversion regained the Scarlet lead but this was dashed just a few minutes later from another Malone penalty. In a breathtaking finish Hercus secured a three pointer with just eight minutes of play remaining; the Scarlets held onto their one point lead to edge into the final.

The 2005–2006 Powergen Cup Final proved to be a vigorous affair from the kick-off as London Wasps had a man stretchered off in the first minute of the game. Both sides failed to step up a gear after this occurrence but the Scarlets took advantage of the shaken Wasps’ defence as they notched an early try. Fullback Barry Davies attained the score for the Welsh region with Mike Hercus successfully converting his effort. Hercus though missed two subsequent penalties as the Guinness Premiership side gathered momentum in the first half. Mark van Gisbergen and Hercus swapped a penalty each before another Irishman left the field; Simon Easterby followed compatriot Jonny O’Connor on the stretcher due to tough tackling. Soon afterwards Jeremy Staunton intercepted a Clive Stuart-Smith pass to send Tom Voyce over for his first try of the game as Wasps drew the points level at ten apiece just as the teams were about to head into the Twickenham dressing rooms.

On the restart Stuart Abbott made a superb break to send man-of-the-match Voyce over to complete his brace, sending the London team into the lead in the process for the first time in the match. As the drizzling rain made playing conditions awkward the Scarlets failed to amass any further points in the second period of play. Van Gisbergen slotted over two penalties whilst a drop goal from replacement fly half Alex King secured a healthy advantage for the English side. Wasps prevented the Scarlets scoring in the second half of the game to cement their 26-10 victory and the triumph of winning the Powergen Cup.

Scarlets Coach Gareth Jenkins had hoped to sign off from his era at Stradey Park with the Powergen Cup in his hands but instead blamed ‘sloppy finishing’ and not the loss of Captain Easterby for their defeat. However, the soon-to-be Welsh Head Coach praised the new format of the Anglo-Welsh competition, adding that it was ‘fitting that there was an English and a Welsh club in the final’. It was now hoped that by raising the bar of Cup rugby that Welsh regional representation in the latter stages of the cup competition would be replicated and multiplied in future seasons.