Dan Robson placed Wasps on the brink of qualification for the knockout phase of the Champions Cup by plundering a last-gasp try that sealed a 17-14 victory over Toulouse.
Trailing 14-10 with 58 seconds left on the clock, replacement scrum-half Robson capitalised on his opponents' temporary loss of focus by taking a quick penalty five yards out and diving over.
Toulouse appeared to have sealed victory in a ferociously-competitive Pool Two when referee John Lacey awarded a controversial 72nd-minute penalty try for Danny Cipriani entering from the side.
Cipriani was sent to the sin-bin as a result and Wasps, who had fought their way back into the lead through a superb solo try from Elliot Daly, were staring at a nervy final weekend of the pool stage next weekend.
But the quick thinking of Robson rescued them in the dying moments, bringing a hard-fought clash to a dramatic conclusion and placing them in the driving seat in their group.
Twice inside the opening five minutes Wasps counter-attacked from deep inside their own half, Christian Wade and Kurtley Beale almost combining to score before Thomas Young was pulled back for a forward pass as he looked to touch down.
Scrum-half Joe Simpson, making his 200th club appearance, was heavily involved and the gaps continued to appear as Cipriani weaved through the first line of defence before Lacey's whistle intervened.
Toulouse rued two simple missed penalties from fly-half Jean-Marc Doussain that should have nudged them ahead, and they were repeatedly opened up when the home side probed for gaps.
Jimmy Gopperth succeeded where Doussain had failed by landing the first points of the afternoon and the half ended with Wasps under pressure as they were shoved downfield.
Simpson failed to appear after the interval due to a wrist problem and the Premiership leaders were unable to stamp their authority on the game, their scrum beginning to crumble as the prelude to Toulouse plundering the first try.
Thierry Dusautoir muscled his way upfield, giant hooker Christopher Tolofua produced a clever off-load and on hand to force his way over was Yoann Huget.
Wasps suffered a further setback when diminutive wing Christian Wade was sin-binned for lifting Francois Cros above the horizontal, an achievement in itself given the size of the French back row.
The match was finely poised and it was Wasps who landed the next telling blow through the footwork of Daly, who stepped into the gap between two forwards and cantered home from close to the half way line with no last line of defence to beat.
Toulouse wilted in the final quarter when the rivals met in round two but showed no signs of throwing in the towel at the Ricoh Arena and they responded magnificently to leaking the touch down.
A maul arrowed its way upfield until replacement prop Vasil Kakovin peeled off and drove over the line only for Cipriani to snatch the ball from his grasp before he could touch down.
Lacey penalised Cipriani and awarded the penalty try but Wasps had the last words through the smarts of Robson, who had replaced the stricken Simpson.
