A battling second-half showing from former champions Leicester Tigers secured a vital 23-19 victory over ASM Clermont Auvergne and ensured Pool Four remains a three-horse race.
Tigers trailed by nine points at the break but won the second period by 13 to claim success at Welford Road.
Having lost the reverse encounter 30-12 in France last week, the 2001 and 2002 Heineken Cup winners knew anything but a third victory of the pool stages would leave their European hopes hanging by the thinnest of threads.
And when a 39th minute converted try from Sitiveni Sivivatu gave the French giants a 16-7 lead, one of the tournament's most accomplished sides were staring down the barrel of an early Heineken Cup exit.
But a Julian Salvi riposte early in the second period brought Tigers right back into the game, with the boot of Toby Flood doing the remainder of the damage to gain immediate revenge on Vern Cotter's men.
Clermont opened up an initial six-point lead thanks to a drop goal apiece from David Skrela and Morgan Parra but it was Leicester who crossed for the game's opening try.
Tigers centre Manu Tuilagi, who was one of two Leicester players to be sinbinned at the Stade Marcel Michelin last weekend, powered through some weak Clermont tackling after taking Flood's inside ball following clean lineout ball on the edge of the 22.
Flood converted from directly underneath the posts to hand the hosts a 7-6 advantage with 16 minutes gone but the remainder of the half belonged to Clermont.
A penalty from Parra saw the visitors regain the lead as the game reached the 20-minute mark. A second missed three-pointer from Flood then allowed Clermont to stay ahead before they extended their lead on the stroke of half-time.
Superb foraging work from openside Alexandre Lapandry put Clermont on the front foot, with Lee Byrne supplying the scoring pass to Sivivatu 25 metres out. The former All Black wing cantered home almost unopposed to give the half-time team talks an altogether different feel as Parra's conversion saw Clermont hold a 16-7 lead at the break.
Leicester responded brilliantly, however, as they collected a quick-fire 10 points in the first eight minutes after the interval.
A well-struck penalty from Flood wide on the left brought Tigers to back within a single score before Salvi powered through from 20 metres out after Ben Youngs' half break had caught Clermont napping.
Parra gave Clermont the lead for a final time on 55 minutes but two further successful penalties saw Tigers home in front of a crowd of more than 20,000.
But while it was Leicester who won today's battle, Clermont arguably won the war as they picked up five points compared to Tigers' four over the back-to-back fixtures in Round Three and Four.
Tries: Tuilagi, Salvi
Cons: Flood 2
Pens: Flood 3
Pens: Parra 2
DG: Skrela, Parra
Leicester Tigers: 15 Geordan Murphy (captain), 14 Horacio Agulla, 13 Matt Smith, 12 Manu Tuilagi, 11 Alesana Tuilagi, 10 Toby Flood, 9 Ben Youngs, 8 Thomas Waldrom, 7 Jules Salvi, 6 Tom Croft, 5 George Skivington, 4 Louis Deacon, 3 Martin Castrogiovanni, 2 George Chuter, 1 Boris Stankovich.
Replacements: 16 Rob Hawkins, 17 Julian White, 18 Dan Cole, 19 Steve Mafi, 20 Ben Woods, 21 Sam Harrison, 22 Billy Twelvetrees, 23 Scott Hamilton.
ASM Clermont Auvergne: 15 Lee Byrne, 14 Sitiveni Sivivatu, 13 Regan King, 12 Wesley Fofana, 11 Julien Malzieu, David Skrela, 9 Morgan Parra, 8 Julien Bonnaire (captain), 7 Alexandre Lapandry, 6 Gerhard Vosloo, 5 Jason White, 4 Jamie Cudmore, 3 Clément Ric, 2 Ti'i Paulo, 1 Lionel Faure.
Replacements: 16 Benjamin Kayser, 17 Vincent Debaty, 18 Daniel Kotze, 19 Nathan Hines, 20 Elvis Vermeulen, 21 Kevin Senio, 22 Brock James, 23 Gavin Williams.
Referee: Nigel Owens (Wales)
Assistant referees: Gwyn Morris (Wales), Jonathan Mason (Wales)
TMO: Derek Bevan (Wales)
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