Toulouse edged Saracens in a thrilling European Cup clash in front of 61,000 at Wembley Stadium.
Louis Picamoles' try 11 minutes from time was converted by Jean -Marc Doussain as the four-time champions came from behind to win.
But that was only after Owen Farrell saw a last-gasp drop goal fall agonisingly short amid a thrilling climax to this compelling Pool Three clash.
Toulouse are now four points clear at the top of the pool while Saracens, who saw Chris Wyles cross after just eight minutes, picked up a losing bonus point despite their first loss of the season.
A British record attendance for a European Cup pool game crowded inside the iconic London venue and were treated to an enthralling game.
Saracens were unbeaten at home and abroad this season but Toulouse flexed their muscles in the scrum in the opening minutes with a sign of what was to come.
However, Luke McAllister suffered an off-day with the boot and failed to capitalise on his forwards' good work, missing three kicks in the first half.
That looked set to come back to haunt the French when Wyles sailed over in the eighth minute.
The try came as a result of some ferocious tackling that clearly rattled the former champions.
Clement Poitrenaud fumbled in midfield and the Saracens backs took full advantage as England pair David Strettle and Chris Ashton combined to send Wyles racing behind the posts. Farrell converted and Saracens led 7-0 early on.
Strettle was sinbinned on 19 minutes for a cynical infringement at the breakdown and Toulouse immediately struck back.
Christophe Tolofua was at the tail of a devastating driving lineout as the Toulouse pack rumbled over the line from distance.
Doussain converted after taking over the kicking duties from McAllister to level the scores.
However, Farrell landed two kicks before half-time for a 13-7 lead at the interval.
Guy Noves rang the changes at the break but a third penalty by Farrell took Saracens out of seven-point range of Toulouse.
Census Johnston provided a battering ram and Maxime Medard made a half-break but the Saracens defence proved equally impressive.
But the French had the edge at the set-piece and when Poitrenaud and Yoann Huget earned a scrum five metres out when they floored Alex Goode, they went for the jugular.
A huge shove by the front row put replacement No8 Picamoles on the front foot to stretch out and score with 69 minutes gone.
That set up a nail-biting climax and, after Farrell fell-short with a 55-metre penalty, the England flyhalf's late drop goal did not have the legs.
Pens: Farrell 3
Tries: Tolofua, Picamoles
Cons: Doussain 2
Saracens: 15 Alex Goode, 14 Chris Ashton, 13 Chris Wyles, 12 Duncan Taylor, 11 David Strettle, 10 Owen Farrell, 9 Richard Wigglesworth, 8 Ernst Joubert, 7 Will Fraser, 6 Billy Vunipola, 5 Alistair Hargreaves, 4 Steve Borthwick (captain), 3 Matt Stevens, 2 Schalk Brits, 1 Mako Vunipola.
Replacements: 16 Jamie George, 17 Rhys Gill, 18 James Johnston, 19 George Kruis, 20 Kelly Brown, 21 Neil de Kock, 22 Marcelo Bosch, 23 Joel Tomkins.
Toulouse: 15 Maxime Medard, 14 Yoann Huget, 13 Florian Fritz (captain), 12 Clement Poitrenaud, 11 Hosea Gear, 10 Luke McAlister, 9 Jean-Marc Doussain, 8 Gillian Galan, 7 Thierry Dusautoir, 6 Yannick Nyanga (c), 5 Joe Tekori, 4 Yoann Maestri, 3 Census Johnston, 2 Christopher Tolofua, 1 Schalk Ferreira.
Replacements: 16 Chiliboy Ralepelle, 17 Gurthro Steenkamp, 18 Yohan Montes, 19 Gregory Lamboley, 20 Romain Millo-Chluski, 21 Jano Vermaak, 22 Gael Fickou, 23 Louis Picamoles.
Referee: Nigel Owens (Wales)
Assistant referees: Sean Brickell (Wales), Wayne Davies (Wales)
TMO: Derek Bevan (Wales)
Lwicester Tigers 34-3 Treviso
An Adam Thompstone try with the final play of the game saw Leicester Tigers pick up maximum points with a 34-3 win against Treviso on Friday.
The former London Irish wing darted over with the clock already in the red just as it seemed as though the Tigers would have to settle for a four-point victory.
Thompstone's heroics sent the Welford Road crowd wild after Man of the Match Thomas Waldrom, Lions Test star Tom Youngs and American wing Blaine Scully had touched down to put the game beyond Benetton.
The result sees the 2001 and 2002 European Champions lead Pool Fivw with six points, although the winners of Montpellier versus Ulster will overtake them at the top tomorrow afternoon.
A slow start saw the game remain scoreless for the first 16 minutes, although Treviso would have got things moving had Mat Berquist succeeded with a fourth minute penalty attempt from five metres inside his own half.
Leicester enjoyed plenty of possession and came close to the first try with 13 minutes gone when Scully gathered a kick downfield but he was dragged into touch by Christian Loamanu just as he attempted to touch down.
The Tigers did go ahead courtesy of Toby Flood's first penalty on 17 minutes and the England flyhalf added a second eight minutes later to make it 6-0.
Treviso scrumhalf Tobias Botes had become the first visiting player to see yellow moments earlier after Waldrom and Graham Kitchener had taken Leicester to within five metres but Flood's three pointer proved to be their only points in the Italian international's absence.
The driving rain continued to make life difficult for both teams in the East Midlands but Leicester finally crossed for their first try with two minutes of the first half remaining.
Flood opted to kick a close-range penalty to touch and the Tigers skipper was immediately rewarded by his pack as they drove the lineout onwards and Waldrom dived over to make it 11-0.
The conversion from Flood handed Leicester a 13-0 lead at the break but Botes finally got Treviso off the mark with a penalty seven minutes after the interval.
It was almost all Tigers from there on in, though, with Treviso's indiscipline costing them dear.
A brace of further yellow cards in the space of two minutes to captain Antonio Pavanello and wing Loamanu for offside and a high tackle respectively gave Leicester a two-man advantage and they capitalised almost straight away.
Hooker Youngs drove over from another close-range lineout after 56 minutes and Flood converted to leave Treviso with a mountain to climb at 20-3 down.
Uncharacteristic handling errors prevented Leicester from initially adding to their tally but Scully made the most of the extra space out wide to dive over following Jordan Crane's pass with 15 minutes left to play.
Again, Flood converted, this time from the touchline, and Leicester were 27-3 clear and in sight of a try-scoring bonus point.
That bonus point seemed destined to go begging until Thompstone took Ed Slater's well-timed pass out wide on the left, before handing off Luke McLean on his way to what could be a crucial score come the closing stages of the pool next January.
For Leicester Tigers:
Tries: Waldrom, Youngs, Scully, Thompstone
Cons: Flood 4
Pens: Flood 2
Leicester Tigers: 15 Niall Morris, 14 Blaine Scully, 13 Vereniki Goneva, 12 Dan Bowden, 11 Adam Thompstone, 10 Toby Flood (captain), 9 Ben Youngs, 8 Thomas Waldrom, 7 Julian Salvi, 6 Ed Slater, 5 Geoff Parling, 4 Graham Kitchener, 3 Dan Cole, 2 Tom Youngs, 1 Logovi'i Mulipola.
Replacements: 16 Neil Briggs, 17 Boris Stankovich, 18 Fraser Balmain, 19 Louis Deacon, 20 Jordan Crane, 21 David Mele, 22 Owen Williams, 23 Terrence Hepetema.
Treviso: 15 Luke McLean, 14 Andrea Pratichetti, 13 Luca Morisi, 12 Alberto Sgarbi, 11 Christian Loamanu, 10 Mat Berquist, 9 Tobias Botes, 8 Robert Barbieri, 7 Alessandro Zanni, 6 Manoa Vosawai, 5 Valerio Bernabo, 4 Antonio Pavanello (captain), 3 Lorenzo Cittadini, 2 Enrico Ceccato, 1 Michele Rizzo.
Replacements: 16 Franco Sbaraglini, 17 Ignacio Fernandez Rouyet, 18 Pedro di Santo, 19 Marco Fuser, 20 Dean Budd, 21 Marco Filippucci, 22 Fabio Semenzato, 23 James Ambrosini.
Referee: Pascal Gauzère (France)
Assistant referees: Laurent Cardona (France), Patrick Pechambert (France)
TMO: Philippe Bonhoure (France)