EMI Buendia scored with the last kick of the game as Aston Villa stunned Arsenal to move three points behind the Premier League leaders.
Leandro Trossard’s sixth goal of the season looked to have earned a point for Arsenal after he cancelled out Matty Cash’s opener.
But Buendia struck in the 95th minute as Unai Emery’s side moved into second in the table.
Arsenal, who blew Bayern Munich and Tottenham away last month, suffered their first defeat in the league since losing 1-0 at Liverpool in August.
Villa Park erupted after substitute Buendia scored to give Villa their seventh straight game in all competitions.
Eberechi Eze had a goal disallowed for offside before the hosts took a first-half lead when Arsenal – especially Eze – switched off to allow Cash to drill in at the far post.
Arsenal emerged re-energised after the break when Mikel Arteta introduced Viktor Gyokeres and Trossard, who levelled with his 50th Premier League goal, having already gone close.
Emi Martinez brilliantly tipped Martin Odegaard’s shot over as Arsenal looked for a winner, but Buendia stole the points in dramatic style, curling in after Arsenal failed to clear.
The talk of Villa being in the title race will only intensify now.
It was a dramatic finish – one of the most significant at Villa Park for a while – but it was Villa who prevailed to underline they could have the staying power.
Putting them in title contention perhaps still seems fanciful as the squad is not as deep as Arsenal or Manchester City’s and Villa remain restricted by profit and sustainability rules.
But the facts are inescapable. Villa are second, before City’s game with Sunderland later on Saturday, and have won nine of their past 10 league games.
The neutral would say a point would have been a fair reflection of an entertaining game in which both teams refused to settle for a draw.
That is where Emery’s side are and what he demands. Emery would not have been happy with a point after Villa went ahead.
Buendia’s strike shows how Emery’s men can power on and drive through one of their biggest challenges.
Buendia was expected to leave in the summer after spending the second half of last season on loan at Bayer Leverkusen, and his resurgence has surprised even those at the club.
But he embodies Villa right now, an underdog who is taking his game to new heights and ready to cause an upset.