England - Arsenal manager Arsene Wenger criticised his side's lack of concentration after they squandered a two-goal lead in the last 10 minutes to lose 3-2 against struggling Wigan.
The Gunners seemed certain to beat Roberto Martinez's side on Sunday after goals from Theo Walcott and Mikael Silvestre gave them a comfortable advantage going into the last 10 minutes at the DW Stadium.
But Ben Watson reduced the deficit and Titus Bramble punished an error by goalkeeper Lukasz Fabianski before an injury-time winner from Charles N'Zogbia shattered Arsenal's title dreams and lifted Wigan clear of the relegation zone.
Wenger was furious with his team's failure to close out a victory that would have moved them to within three points of leaders Chelsea.
"It is difficult to understand," Wenger said. "Maybe the players felt too much comfort and you have to keep focused for 90 minutes or you get punished.
"You cannot be happy with the way we conceded the goals. There was a lack of urgency there and we were punished.
"I believe at our level you don't want to give excuses and you want to show your character in every single game. You can always find an excuse but that is not important."
Wenger wants his side to react in a positive way in the remaining fixtures against Manchester City, Blackburn and Fulham, although lifting the dressing room after gifting three points to the opposition as they did here will be no easy task.
The French coach refused to discuss his side's title hopes and said only: "We have to focus and try to win our next games."
Walcott's classy finish after a fine through ball from Nicklas Bendtner and Silvestre's glancing header from Samir Nasri's corner sent Arsenal into cruise control after 48 minutes.
But, led by N'Zogbia and 19-year-old Victor Moses, Wigan poured forward and no-one in the ground was surprised when Watson slotted home from 12 yards out with 10 minutes to go to breathe some life back into the home side.
With the final whistle approaching, Fabianski -- playing because of an injury to Manuel Almunia -- made the fatal mistake of dropping a corner onto Bramble's head and he nodded in before N'Zogbia thrashed home a 25-yarder with practically the last kick.
Martinez said: "Without a doubt that was (our) best win of the season. We have folded many times this season.
"We have been through some painful lessons this season, from the 9-1 against Spurs and, to come back from 2-0 down, I don't think too many do that, so I think we have learnt from our experiences.
"You don't get results like by accident, we deserved it."
Yet despite the huge boost in confidence and momentum the win is likely to give Martinez's squad, plus the fact the victory puts them comfortably clear off the relegation zone, the Spaniard is not ready to relax yet.
"We shouldn't get carried away, after Wednesday's (0-0) draw with Portsmouth, everybody said we were nearly relegated and now we should not think we are safe," he said.
"Not many come back from 2-0 down against Arsenal so we are really, really pleased.
"It has been a tough week for the players after not scoring against Portsmouth in the week but we deserved it.
"Moments like this are vital for our football club and our fans. I'm extremely proud of my players."