Premier League: Bolton 2 Arsenal 1
Arsenal's league title hopes are all but over after Bolton substitute Tamir Cohen grabbed a last-minute winner at the Reebok Stadium.
Cohen celebrated by removing his Wanderers top to reveal a T-shirt complete with a photograph of his late father Avi, the former Liverpool defender.
Tamir's father was killed in a motorcycle crash last December and the 27-year-old midfielder dedicated his match winner to his memory.
The Gunners had gone behind to a 38th minute strike from Daniel Sturridge, currently on loan from rivals Chelsea.
They pulled level just after half-time through a Robin van Persie goal moments after Kevin Davies had missed a penalty for the home side.
But, despite piling on the pressure in search of three points, they were stung by Cohen's 90th minute clincher.
It was the perfect response from Bolton, following their 5-0 mauling by Stoke in the FA Cup semi-final last week.
However, Arsenal's first league defeat of 2011 leaves them nine points behind Manchester United and seemingly heading for their sixth season without a trophy.
Arsene Wenger's side started brightly and were almost ahead inside five minutes. Theo Walcott found space on the right but his shot was parried by Jussi Jaaskelainen and Samir Nasri's follow-up effort was blocked by a combination of Gary Cahill and Zat Knight.
Jaaskelainen then tipped Cesc Fabregas's shot round the post while a Van Persie volley was blocked away by Cahill.
But Bolton forced their way back into the game and should have gone ahead when Chung-Yong Lee headed for goal but hit his shot straight at Wojciech Szczesny in the Arsenal goal.
Wanderers though went ahead in the 38th minute when Cahill powerfully headed Lee's corner against Nasri guarding the post and Sturridge followed up to head home.
And Bolton should have doubled their lead moments after the break, when they were awarded a penalty for Johann Djorou's challenge on Sturridge.
But Arsenal keeper Szczesny, who gave away a spot-kick himself in the midweek derby draw at Spurs, saved Kevin Davies' tame effort.
Moments later the Gunners broke to the other end of the pitch where Fabregas teed up Van Persie to smash home from the edge of the box.
With 20 minutes to go, Arsenal should have been ahead when Nasri beat the offside trap and went for power, firing straight at Jaaskelainen, and when the ball came back to him, Cahill got back to clear his second effort off the line.
Arsenal piled forward for the last quarter of an hour but failed to force a save from Jaaskelainen.
And Bolton pinched all three points in the last minute when Cohen headed home Matthew Taylor's corner.