The Ospreys let a 26-8 lead slip at Welford Road on Sunday, as Leicester fought back to claim a stirring 32-32 Heineken Cup draw.
The visitors notched 23 unanswered first-half points as they fought back from 8-0 down and an early Johne Murphy try to claim what looked to be an unassailable half-time lead in a belting game of rugby.
But Leicester are made of stern stuff and produced a mesmeric second half to get their way back into the game, claiming a crucial bonus point for scoring four tries, which in this tightest of groups might yet count for so much.
The Tigers, already decimated by injuries, lost four more key players before kick-off and found themselves 26-8 down late in the first half.
The Ospreys had stormed ahead with tries from Shane Williams and Tommy Bowe - plus a faultless kicking performance from teenage fly-half Dan Biggar, who finished with 22 points.
Leicester's changing room may have resembled a scene from MASH - but nothing could damage their age-old fighting spirit as the Tigers mounted a dramatic comeback.
Man of the match Billy Twelvetrees added to Johne Murphy's early try, before Argentinian winger Lucas Amorosino and then Jeremy Staunton earned the Tigers a share of the spoils and a four-try bonus point.
Leicester have not lost at Welford Road in more than a year, and the Ospreys will be kicking themselves at letting such a golden opportunity slip through their fingers.
The Tigers - already without the likes Geordan Murphy, Toby Flood and Sam Vesty - were forced into a major backline reshuffle after Harry Ellis, Matt Smith and centre pairing Aaron Mauger and Dan Hipkiss were all ruled out.
Things got even worse for the Tigers at the interval when Anthony Allen was replaced in midfield by the former All Black flanker Craig Newby.
At first, the Tigers appeared unaffected by all the changes and raced into an early 8-0 lead as Julian White demolished the Ospreys scrum and Allen made an enterprising start as a makeshift outside-centre.
Allen ran on to Staunton's long pass and carved his way through the Ospreys line to set up the Tigers' opening try, which was scored in the corner by Murphy.
Leicester had the Ospreys' scrum under immense pressure, and White won consecutive penalties - the first of which Staunton fired wide from 55metres but the second he slotted from under posts.
White then looked at referee Alain Rolland in disbelief when he was penalised at the next scrum, and Biggar landed the long-range kick to keep the Ospreys in touch.
White got his revenge at the next set-piece. But Staunton missed again, and the Ospreys began to turn the tables - with their incisive back division punishing the patched-up Tigers.
Biggar landed a second penalty and was then involved twice as the Ospreys surged into the lead with a try from Shane Williams.
The teenage fly-half followed his own steepling up-and-under, which was too hot for Jordan Crane to handle, and took a beautifully delayed inside pass from James Hook to send Williams away for the try.
Biggar slotted a cool drop-goal before Bowe pounced on another mistake in the Leicester ranks - scooping up a loose ball to score unopposed under the posts.
Another Biggar penalty opened the Ospreys a 26-8 lead - before the Tigers found their claws again and staged a spirited comeback, with Allen again playing a key role.
The former Gloucester centre managed to squeeze a pass outside for Twelvetrees, who crashed over in the corner and then dusted himself down to assume the kicking duties from Staunton and land the conversion.
Biggar's seventh consecutive place-kick extended the Ospreys' lead to 29-15. But the Tigers responded by throwing caution to the wind and worked an excellent third try for Amorosino.
From a Tigers scrum near half-way, James Grindal attacked the blind-side - and Hamilton slipped the scoring pass for the Argentinian winger to tee up a dramatic finale.
Biggar eased the pressure for the Ospreys with another penalty, but Twelvetrees responded for the Tigers and then sparked the vital attack with five minutes remaining.
Staunton's run took him within two metres of the line.
It appeared he had wasted the chance when he failed to pop the pass to Murphy on his outside, but he drove on for the line - and Twelvetrees kicked the conversion to earn a dramatic draw.
Tries: Murphy, Twelvetrees, Amorosino, Staunton
Cons: Twelvetrees 3
Pens: Staunton, Twelvetrees
For the Ospreys:
Tries: Williams, Bowe
Cons: Biggar 2
Pens: Biggar 5
Drop goal: Biggar
Leicester Tigers: 15 Scott Hamilton, 14 Lucas Amorosino, 13 Anthony Allen, 12 Billy Twelvetrees, 11 Johne Murphy, 10 Jeremy Staunton, 9 James Grindal, 8 Jordan Crane, 7 Lewis Moody, 6 Tom Croft, 5 Ben Kay, 4 Louis Deacon, 3 Julian White, 2 George Chuter, 1 Marcos Ayerza.
Replacements: 16 Joe Duffey, 17 Boris Stankovich, 18 Martin Castrogiovanni, 19 Geoff Parling, 20 Craig Newby, 21 Ben Youngs.
Ospreys: 15 Lee Byrne, 14 Nikki Walker, 13 Tommy Bowe, 12 James Hook, 11 Shane Williams, 10 Dan Biggar, 9 Mike Phillips, 8 Ryan Jones, 7 Marty Holah, 6 Jerry Collins, 5 Jonathan Thomas, 4 Alun Wyn Jones, 3 Cai Griffiths, 2 Huw Bennett, 1 Paul James.
Replacements: 16 Richard Hibbard, 17 Craig Mitchell, 18 Ryan Bevington, 19 Ian Gough, 20 Filo Tiatia, 21 Jamie Nutbrown, 22 Andrew Bishop, 23 Sonny Parker.
Referee: Alain Rolland