Paris - Four-time champions Toulouse came from behind to stun Saracens 17-16 in front of more than 60,000 fans at Wembley in a European Cup Pool 3 match on Friday.
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The French Top 14 giants are now in control of the group following two wins out of two while the Londoners had to settle for a defensive bonus point, in front of a record crowd for a Pool game in England.
Sarries missed out on a dramatic late victory when Owen Farrell's drop-kick fell agonisingly short.
"This result puts Toulouse in control of the group to a degree, but we still have a lot to play for," said Saracens director of rugby Mark McCall.
"We must do the job when we have Zebre back to back in December."
Chris Wyles had given the hosts the lead with the opening try of the match but close-range scores from forwards Christopher Tolofua and Louis Picamoles turned the game in Toulouse's favour.
The French made a haphazard start that cost them the first try of the match as Clement Poitrenaud took his eye off the ball with Chris Ashton storming in to make a hit and dropped Luke McAlister's pass.
Saracens recovered the ball and quickly managed to to isolate centre Wyles up against No.8 Gilian Galan.
Wyles broke the gain-line and exchanged passes with Ashton before running round under the posts, with Farrell converting.
It could have been two tries as Toulouse turned over ball in their own half again when Maxime Medard spilled it in the tackle and Ashton kicked through, only for the backtracking Thierry Dusautoir to save his side.
Toulouse were no more composed in attack as McAlister missed three penalty attempts, the last from practically right in front of the posts, while he sliced two clearance kicks into touch with little territorial gain.
Saracens had been warned for their indiscipline, though, and referee Nigel Owens lost patience when David Strettle tackled Yannick Nyanga off the ball and was promptly sent to the sin-bin.
Toulouse kicked for touch instead of goal and won the line-out before forming a maul and driving hooker Tolofua over the line.
Scrum-half Jean-Marc Doussain took over kicking duties and levelled the scores at 7-7.
But back to a full contingent, Saracens were quickly into the ascendancy and two Farrell penalties gave them a six-point cushion at half-time, while McAlister's miserable game ended in a bicep injury five minutes before the break.
Farrell stretched Sarries' lead early in the second period but Doussain landed his own kick 13 minutes from time to keep Toulouse within a converted try of the lead.
Doussain forced a turnover deep in the Toulouse half and then a kick and chase from Yoann Huget forced Andy Goode to touch down behind his own tryline.
France No.8 Picamoles picked and went from the back of the five-metre scrum and forced his way over.
With Doussain kicking the extras, Toulouse had a one-point lead with 10 minutes to play.
Saracens battled until four minutes into overtime when Farrell's drop-kick attempt was partially blocked and dropped just a yard short of the crossbar.
Toulouse coach Guy Noves admitted that McAlister will miss next weekend's French Top 14 clash against Toulon.
"We fear it's a rupture of the ligament in the left forearm," said Noves.
"He is already out of contention for the next match."
In Pool 5, Leicester bounced back from last week's defeat to Ulster with a comfortable 34-3 win over Italians Treviso.
Winger Adam Thompstone's last minute try ensured the Tigers earnt an attacking bonus point following earlier scores from No.8 Thomas Waldrom, hooker Tom Youngs and winger Blaine Scully, with fly-half Toby Flood kicking 14 points.