A pit is opening beneath Leicester's feet from which they will do well to emerge. They lost the first of their two titles at Twickenham on Saturday, when the EDF Energy Cup slipped away to the Ospreys without much of a shot fired in its defence and, if they are not careful, they will be unable to defend the Guinness Premiership because they will not reach the play-offs.

A different XV are due to start the Premiership match away to Bath tomorrow evening and, if they lose and London Wasps beat Sale Sharks in High Wycombe, Leicester will be sixth in the table and clinging on by their fingernails to European qualification for next season. “We have to ask this other group of players to take responsibility now,” Marcello Loffreda, the Leicester coach, said.

If Leicester seek an example to follow, they need look only as far as the Ospreys, who became the first Welsh region to win the EDF Energy Cup and did so with a becoming grace. They arrived at Twickenham with a burning desire to compensate their supporters for the flat display against Saracens six days earlier that cost them a place in the Heineken Cup semi-finals and, although not at their best, they played the secure game of which Leicester, in their heyday, would have been proud.

“We have learnt more about rugby playing against Leicester than anyone else,” Lyn Jones, the Ospreys coach, said, with reference to three earlier games against the Midlands club, all of which they lost. “They have been a great side, they're still a great side, but playing against them we learnt so much about the game; about ourselves.”

Jones is convinced that the Ospreys captain, his namesake, Ryan, who led Wales to their grand slam in March, will lead next year's Lions tour to South Africa, although the No8 would be content just to guide the Ospreys in a winning European campaign. “As a captain, I'm still learning and developing,” Ryan Jones said.

“I've played under Martin Corry, under Alfie [Gareth Thomas] and they were superb, they're the people you learn from. But you have to do it your way, you have to be true to yourself.”

As a player, Jones brings all the right values to his game, a work ethic of which Corry, the Leicester and former England captain, would be proud and a regard for his team to which they respond. They rode out the early Leicester storm, they defended like lions when their opponents camped on their line and they played most of the worthwhile rugby.

But how easy Leicester made it for them. Three weeks earlier, in the semi-finals of the same competition, they were assertive, accurate and swift in beating Wasps in Cardiff; on this occasion their defence and discipline were slipshod in the extreme, their scrum did not inconvenience the Ospreys and their lack of imagination when they did achieve potential scoring positions was astounding.

Loffreda denied the suggestion that heavy rain at the start affected their tactical approach, but the Leicester midfield looked as though they had never played together. Only Johne Murphy at full back and Harry Ellis, the scrum half, emerged with any credit, whereas the Ospreys, inspired by a wonderful display from Lee Byrne, found heroes all over the pitch, not the least Andrew Bishop, Gavin Henson's replacement at centre.

Even Bishop would not have expected to score the first-half try that helped the Welsh region to take the lead. But he ran an inside switch at two pairs of Leicester defenders and not one could stop him. On another day, the Ospreys might have scored a further two tries before the interval; instead they took advantage early in the second half of a Leicester knock-on to run from halfway and James Hook gave Alun-Wyn []Jones a simple touchdown.

“It is a breakthrough result for us,” Lyn Jones said. “Twelve months ago, when we lost this final to Leicester, we all understood where we were as a squad. It's a horrible experience, but it's part of growing up and if you keep improving, one day you'll cross the line.”

Scorers: Leicester: Penalty goal: Goode (6min). Dropped goal: Goode (17). Ospreys: Tries: Bishop (23), A-W Jones (48). Conversions: Hook 2. Penalty goals: Hook 3 (58, 73, 76).

Scoring sequence (Leicester first): 3-0, 6-0, 6-7 (half-time), 6-14, 6-17, 6-20, 6-23.

Leicester: J Murphy; O Smith, D Hipkiss, A Mauger, A Tuilagi (rep: T Varndell, 77); A Goode, H Ellis; B Stankovich (rep: J White, 52), G Chuter, M Castrogiovanni (rep: Stankovich, 72; rep: B Kayser, 75), L Deacon, B Kay, M Corry, BHerring (rep: T Croft, 58), J Crane.

Ospreys: L Byrne; J Vaughton (rep: A Brew, 77), S Parker, A Bishop (rep: J Spratt, 76), S Williams; J Hook (rep: G Owen, 77), J Marshall; P James (rep: D Jones, 72), R Hibbard (rep: H Bennett, 67), A Jones (rep: James, 76), A-W Jones, I Evans (rep: I Gough, 70), R Jones, M Holah, F Tiatia (rep: J Thomas, 70).

Referee: A Rolland (Ireland).

Attendance: 65,756.