Match ends, Arsenal 2, Leicester City 1.
Danny Welbeck threw the Premier League title race wide open when he scored a dramatic winner with only seconds left as Arsenal beat leaders Leicester City.
The Foxes looked set to hold out for a vital draw as a thrilling game went into injury time, despite being reduced to 10 men after Danny Simpson was sent off for a second yellow card early in the second half.
This was until Welbeck, playing his first competitive game since April last year, glanced Mesut Ozil's free-kick past the magnificent Kasper Schmeichel to spark wild celebrations at Emirates Stadium as Leicester lost in the league for just the third time this season.
Jamie Vardy gave the Foxes the lead with a hotly-disputed penalty on the stroke of half-time after he tumbled over Nacho Monreal's outstretched leg.
Substitute Theo Walcott then set up a frantic final 20 minutes with a side-foot finish from Olivier Giroud's superb knockdown.
Leicester still lead the table - but Arsenal's win leaves them only two points clear.
A decisive day for the title?
In those closing seconds, with the Emirates awash with tension and anxiety, it looked like Leicester would secure a point that would feel like a victory to manager Claudio Ranieri and his players.
It would have been a draw achieved with a numerical disadvantage at the home of a title rival - and would have given them four precious points from visits to Manchester City and Arsenal.
Instead, Welbeck's intervention left Ranieri and his men desolate after an outstanding backs-to-the-wall performance, exemplified by the brilliance of keeper Schmeichel as he kept Arsenal at bay, with one late save from Giroud world-class especially notable.
Now they must bounce back at home to Norwich City in their next game - but why should we question them after what they have shown us this season?
As for Arsenal, this result will revive their title hopes as the impact will be just as dramatic for them. It would have felt like a defeat had they not beaten a Leicester side reduced to 10 men for 36 minutes.
So the title landscape has changed - but it is still Leicester at the top of the table.
Welbeck revives Arsenal's challenge
As Arsenal manager Arsene Wenger rightly said after the match, his team were looking down the barrel when they trailed at half-time.
At that point, they were eight points adrift of the Foxes with only 12 games left after this one - a daunting gap.
Walcott's equaliser and that injury-time winner from Welbeck, who has been out for almost a year with a knee injury, was reward for their persistence and effort in the second half.
It was not just vital in the context of this game, it was crucial in the wider context after a poor run of home form which had seen the Gunners fail to win in four league games - with three draws and a defeat - before last week's win at Bournemouth.
Kante simply outstanding
N'Golo Kante arrived at Leicester City in early August as an under-the-radar £6m signing from French side Caen - he should now be a contender for Player of the Year.
When Rio Ferdinand is moved to tweet, "right now Kante is the best tackler/retriever of the ball on the planet", you get some idea of just how good he was at the Emirates.
In the first 45 minutes in particular, the Paris-born 24-year-old gave a masterclass in the arts Ferdinand was talking about. While the likes of Vardy and Riyad Mahrez have rightly claimed the limelight, Kante has been just as influential in the manner in which he retains and regains possession, helping Leicester to set up those trademark counter-attacks.
Tough day for Atkinson
Referee Martin Atkinson was left to handle a tidal wave of pressure and emotion, especially after awarding Leicester that penalty.
It was a tough call, with Vardy clearly accepting the invitation literally extended by Monreal's outstretched leg.
Vardy bought the penalty but it was understandable to see why he gave it - and it is worth noting former Arsenal legends Lee Dixon and David Seaman tweeted their agreement with the decision.
Arsenal fans were demanding every decision after that - and most supporters around the country would be the same - but Atkinson's decision to send Simpson off for two soft fouls was also correct.
It is not just players under stress on these occasions.
Man of the match - Kasper Schmeichel (Leicester City)
The stats you need to know
- Leicester still have not won a league game against Arsenal since November 1994 (P19 W0 D6 L13).
- Vardy has won six penalties in the Premier League this season; twice as many as any other player. In fact, Vardy has won more penalties alone than all of the other 19 Premier League teams this season.
- This was the ninth time this season that Vardy has scored the opening goal of a Premier League game - the most of all PL players.
- Walcott's 70th-minute goal was Arsenal's first shot on target in this match, while Welbeck scored their sixth and final effort on target in this game.
- Leicester named an unchanged starting XI for the sixth successive league game - the longest run this season and the longest in the competition since Arsenal (six games) in May 2015.
- Welbeck's goal was Arsenal's 100th goal scored in 90+ minutes of a Premier League game; more than any other side.
What the managers said...
Arsenal boss Arsene Wenger, speaking to BBC Sport: "The effort, energy, intensity was all good. Leicester defended very well but we had bad luck to be 1-0 down at half-time. We were relentless after that - we should have scored more goals.
"It was a pivotal moment today because the mathematics meant it could be eight points or it could be two points. That is a great change.
"There's a long way to go, we play a lot of big teams. But we had a bad spell where we couldn't win for four games and have now won two on the bounce. We have come out of that bad spell and still have a good chance."
Leicester boss Claudio Ranieri, speaking to Sky Sports: "It was a fantastic match, very fast. I don't know if in a normal match that our two yellows cards was a sending off. They were normal fouls, but not yellow cards. I think the referee was too severe to us for the sending off. 11 v 11, I'm sure we win the match. The match was full of fouls so why send off a player? Come on.
"We know Arsenal are a fantastic team, they move the ball quickly and have skill, but we had to concentrate. We tried to counter-attack and we controlled the match very well.
"We are still top of the table, got two points more - we must carry on and smile. We lost to our opponents - we must say well done."
Arsenal face two cup games in a row as they host Hull in the FA Cup fifth round next Saturday (12:45 GMT) before the first leg of their Champions League last-16 tie with Barcelona at the Emirates the following Tuesday.
Leicester, who are out of the FA Cup, face Norwich at the King Power Stadium in the Premier League on Saturday, 27 February (15:00 GMT).
- 6KoscielnyBooked at 44minsSubstituted forChambersat 45'minutes
- 34CoquelinBooked at 36minsSubstituted forWalcottat 61'minutes
- 16RamseyBooked at 45mins
- 15Oxlade-ChamberlainSubstituted forWelbeckat 83'minutesBooked at 90mins
- 17SimpsonBooked at 54mins
- 28FuchsBooked at 52mins
- 26MahrezSubstituted forWasilewskiat 58'minutesBooked at 90mins
- 14KantéBooked at 57mins
- 11AlbrightonSubstituted forKingat 83'minutes
- 20OkazakiSubstituted forGrayat 61'minutes
- Martin Atkinson
- Shots on Target
Second Half ends, Arsenal 2, Leicester City 1.
Danny Welbeck (Arsenal) is shown the yellow card for excessive celebration.
Goal! Arsenal 2, Leicester City 1. Danny Welbeck (Arsenal) header from the centre of the box to the bottom left corner. Assisted by Mesut Özil with a cross following a set piece situation.
Marcin Wasilewski (Leicester City) is shown the yellow card for a bad foul.
Nacho Monreal (Arsenal) wins a free kick in the attacking half.
Foul by Marcin Wasilewski (Leicester City).
Corner, Arsenal. Conceded by Kasper Schmeichel.
Mesut Özil (Arsenal) wins a free kick in the defensive half.
Foul by Jamie Vardy (Leicester City).
Attempt missed. Theo Walcott (Arsenal) right footed shot from the centre of the box misses to the right. Assisted by Olivier Giroud with a cross.
Attempt missed. Aaron Ramsey (Arsenal) right footed shot from the centre of the box misses to the left. Assisted by Nacho Monreal.
Attempt saved. Olivier Giroud (Arsenal) header from the centre of the box is saved in the bottom right corner.
Attempt saved. Olivier Giroud (Arsenal) left footed shot from the centre of the box is saved in the centre of the goal.
Attempt saved. Danny Welbeck (Arsenal) header from the centre of the box is saved in the centre of the goal. Assisted by Olivier Giroud with a headed pass.
Attempt missed. Per Mertesacker (Arsenal) with an attempt from the centre of the box is close, but misses to the left. Assisted by Mesut Özil following a corner.
Attempt blocked. Per Mertesacker (Arsenal) header from the left side of the six yard box is blocked. Assisted by Alexis Sánchez with a cross.
Corner, Arsenal. Conceded by Marcin Wasilewski.
Attempt saved. Olivier Giroud (Arsenal) header from the centre of the box is saved in the centre of the goal. Assisted by Héctor Bellerín with a cross.
Substitution, Arsenal. Danny Welbeck replaces Alex Oxlade-Chamberlain.