There will, after all, be one more big day for Lawrence Dallaglio, at Twickenham on May 31. The London Wasps captain refused to say farewell to rugby at Adams Park yesterday, driving forward on a tide of emotion into another Guinness Premiership final the club he has served for 18 years, despite the body blow of the loss of Danny Cipriani with a damaged right ankle.

Cipriani, 20, has had to learn swiftly how to deal with triumph and disaster. This has been the fly half’s breakthrough season as an international player and he was looking forward to touring New Zealand with England next month. But Martin Johnson, the England team manager, could only watch from the stand as Cipriani was carried off early in the second half after his leg was trapped underneath him in a double tackle by Alex Crockett and Olly Barkley.

Players from both sides alerted Chris White, the referee, to the serious nature of the injury, but Wasps could not confirm the extent of the problem before Cipriani left for the Lister Hospital, on London’s South Bank. “The only priority for Danny is to be 100 per cent fit again,” Ian McGeechan, the Wasps director of rugby, said in a tone that suggested a visit to New Zealand did not rate high on his agenda. “He’s a talented rugby player, that’s all we should be considering, and we will make sure that happens.”

Cipriani was clearly in agony and, apart from a possible dislocated or broken ankle, there may be ligament damage, too. In that case he could be discounted from England’s autumn internationals, never mind this summer. “Danny will be a better and stronger player when he comes back,” Dallaglio said, but it is not only Wasps who hope that that will be sooner rather than later.

There is every possibility, too, that Tom Voyce will miss the Premiership final after the wing dislocated his left shoulder in a tackle by Butch James in the run that set up his club’s third try. Three attempts to replace the shoulder failed, which, added to the hooking problem - Raphaël Ibañez withdrew with a back injury yesterday morning and his replacement, Joe Ward, hurt his neck at the first scrum - makes this achievement by Wasps among their finest.

Nor was this play-off another great defensive display alone. Three tries to one tells its own story, of a side that can always conjure up a fitting response when their opponents appear to be gaining the upper hand.

No sooner had Bath taken the lead than Wasps rammed home two tries in six minutes and, although Bath continued to dominate territory and possession, they foundered whenever they entered the home 22.

“You need emotion to defend the way we defended, perhaps we save that for the big games,” Dallaglio said. “People like Tom Rees were outstanding but, to a man, they played their part and we have another big day out.”

It will be Wasps’ fourth final since 2003 and they won the previous three. Bath have one more chance of a trophy to reward an outstanding season - they play Worcester in the European Challenge Cup final at Kingsholm next Sunday - but this defeat, and that by Gloucester nine days ago, will have drained them. Barkley, kicking into the wind, missed two penalty attempts that his record this season suggests were well within his compass and they owed their try to a Wasps error. Attempting to play their way out of trouble from their in-goal area, Josh Lewsey dropped a pass from Cipriani, giving Crockett the chance to drop on the ball and score.

In that opening period the Wasps lineout could do nothing right and their scrum was in all sorts of trouble until James Buckland replaced the unfortunate Ward. That the Wasps line remained intact for as long as it did owed much to the defence of Paul Sackey, who gave the giant Matt Banahan not an inch as Bath plied their left wing with ball. But James, named on Saturday in the first South Africa training squad of the season, was inaccurate with his tactical kicking, Bath lost the influential Michael Lipman with facial damage and Wasps put the pieces of their game into place.

It revolved around the charging runs of James Haskell and the swift hands and good lines run by their backs. Fraser Waters claimed the first try, picking an inside line off Riki Flutey after Sackey had done much of the early work. The second fell to Flutey after Sackey joined his line from the blind-side wing and was brought to ground five metres short.

Cipriani converted both to embellish the neat touches he had shown on the rare occasions that Wasps had the ball, but he had departed by the time that Waters and Voyce combined down the short side and Tom Palmer thundered over from ten metres.

Hope flickered for Bath when Waters, flirting once too often with the offside line, was sent to the sin-bin for the final ten minutes, but Wasps, their competitive juices flowing, had the game in their hands and used up the time, with Bath able only to stand and watch.

Scorers: London Wasps: Tries: Waters (30min), Flutey (36), Palmer (59). Conversions: Cipriani 2, Van Gisbergen. Bath: Try: Crockett (26). Conversion: Barkley. Penalty goal: Barkley (56). Scoring sequence (Wasps first): 0-7, 7-7, 14-7 (half-time), 14-10, 21-10.

London Wasps: J Lewsey; P Sackey, F Waters (sin-bin, 70-80), R Flutey, T Voyce (rep: M McMillan, 59); D Cipriani (rep: M van Gisbergen, 49), E Reddan; T Payne (rep: J Hart, 65), J Ward (rep: J Buckland, 28), P Barnard (rep: T French, 56), S Shaw, T Palmer, J Haskell (rep: R Birkett, 76), T Rees (rep: Birkett, 68-74), L Dallaglio (rep: J Worsley, 65).

Bath: J Maddock (rep: N Abendanon, 60); A Higgins, A Crockett (rep: S Berne, 60), O Barkley, M Banahan; A James, M Claassens; D Barnes (rep: D Flatman, 57), P Dixon (rep: R Hawkins, 73), M Stevens (rep: D Bell, 76), S Borthwick, D Grewcock, J Fa’amatuainu, M Lipman (rep: P Short, 28), D Browne.

Referee: C White. Attendance: 10,000.