Match ends, Arsenal 1, Leicester City 0.
Arsenal kept up their top-four chase as a late Robert Huth own goal gave them victory against a stubborn Leicester side.
The home supporters at Emirates Stadium seemed set for a deflating evening before Nacho Monreal's shot found the bottom corner via the German defender's chest four minutes from time.
Alexis Sanchez had rattled the bar and been denied by Huth's last-ditch challenge in the Gunners' best chances before the goal.
But Leicester also threatened, with Riyad Mahrez bringing a superb save out of Petr Cech in the first half, and then had furious penalty appeals turned down at the death.
Arsenal are now three points behind Manchester United and four behind fourth-placed Manchester City having played the same number of games - at least one of the Manchester pair will drop points when they meet on Thursday.
Liverpool, in third, are six points ahead of the Londoners having played two more games.
Arsenal walking the top-four tightrope
Before the match Gunners boss Arsene Wenger insisted that qualifying for a 20th successive season of Champions League football was still possible, but dependent on a "perfect run-in".
This was the first step on perilous tightrope walk that includes the north London derby against Tottenham on Sunday and meetings with Manchester United and Everton in their remaining six games.
There is little room for error and few in the Emirates initially seemed to have confidence in their team delivering the sprint finish necessary.
A patchy attendance - officially numbered at 59,829 - produced a lukewarm atmosphere in the first half, most notable for Leicester fans' appeals for Wenger to stay in his job after his contract expires at the end of the season.
The decisive strike, combined with a late incident in which Christian Fuchs launched a throw-in into Sanchez's shoulder from close range - prompting the Chilean to fall down clutching his face - raised the temperature towards the end.
But Arsenal will need to play better over the rest of their campaign to pull off an improbable late surge into the Champions League places.
More immediately, defeat by Tottenham on Sunday will ensure their local rivals finish above them in the table for the first time since 1994-95 season.
Vardy sees what might have been
Jamie Vardy may have ended up on the losing side, but the match exemplified why the Leicester striker turned down the chance to move to Arsenal in the summer.
Last season's Premier League top-scorer has scored seven goals in 11 games since Craig Shakespeare took over and revived the spirit of that Foxes title-winning season and his searing pace and instinctive play suited the visitors counter-attacking gameplan.
He chased hard up front on his own and almost beat Cech with a snap-shot from Marc Albrighton's pull-back in one of his side's few chances.
Faced with the deep-lying defences that Arsenal often come up against and the Gunners' intricate build-up play, the 30-year-old would have had to make major changes to his game to fit in.
Spite and spice in the final minutes
While the exchange between Fuchs and Sanchez provided a moment of pantomime towards the end, Yohan Benalouane's foul on Olivier Giroud was a more malicious matter.
The Leicester defender planted his studs into the base of Giroud's back as the pair contest a header late on.
Several Arsenal players surrounded referee Mike Jones demanding more than the yellow card shown and, given replays appeared to show Benalouane checking Giroud's whereabouts before launching into the challenge, it could easily have been red.
Man of the match - Nacho Monreal
21 and counting... the key match stats
- Arsenal extended their unbeaten run over Leicester in the Premier League to 21 games. They have not lost since their very first meeting in November 1994.
- The victory saw the Gunners equal their longest home winning streak against a single opponent - 10 successive wins against Everton between January 1997 and September 2005.
- Arsenal have now scored 29 league goals in the final 30 minutes of games in the Premier League this season, the most of any side.
- For Leicester, meanwhile, this was the first time they have failed to score in a Premier League game under Craig Shakespeare - they had done so at least twice in each of the previous seven.
What they said:
Arsenal manager Arsene Wenger: "Every win gives you a little more momentum. I don't have a preference for the Manchester derby, we don't have to look much at the others. We just have to look after ourselves. The target is clear for us.
"Leicester were hard to break down, but we were patient and did not give away any chances."
Leicester manager Craig Shakespeare: "We showed resilience in our defending, but we have not got any points on the board to show for it. We restricted them and were cruelly beaten by a deflected shot. We have got a dejected dressing room in there.
"We have not got enough points yet and we need to put more on the board."
Arsenal take on north London rivals Tottenham on Sunday at 16:30 BST. Leicester travel to West Brom in the league on the day before.
- 34CoquelinSubstituted forRamseyat 75'minutes
- 29XhakaBooked at 82mins
- 3GibbsSubstituted forWelbeckat 68'minutes
- 14WalcottSubstituted forGiroudat 75'minutes
- 7SánchezBooked at 90mins
- 17SimpsonBooked at 38mins
- 29BenalouaneBooked at 80minsSubstituted forGrayat 90'minutes
- 6HuthBooked at 90mins
- 28FuchsBooked at 52mins
- 23UlloaSubstituted forOkazakiat 70'minutes
- Mike Jones
- Shots on Target
Second Half ends, Arsenal 1, Leicester City 0.
Delay over. They are ready to continue.
Delay in match (Arsenal).
Offside, Arsenal. Mesut Özil tries a through ball, but Olivier Giroud is caught offside.
Alexis Sánchez (Arsenal) wins a free kick on the left wing.
Foul by Robert Huth (Leicester City).
Robert Huth (Leicester City) is shown the yellow card.
Laurent Koscielny (Arsenal) wins a free kick in the defensive half.
Foul by Demarai Gray (Leicester City).
Attempt blocked. Shinji Okazaki (Leicester City) right footed shot from the right side of the six yard box is blocked. Assisted by Riyad Mahrez.
Alexis Sánchez (Arsenal) is shown the yellow card.
Alexis Sánchez (Arsenal).
Christian Fuchs (Leicester City) wins a free kick on the right wing.
Attempt missed. Olivier Giroud (Arsenal) left footed shot from outside the box is high and wide to the left. Assisted by Aaron Ramsey.
Substitution, Leicester City. Demarai Gray replaces Yohan Benalouane.
Offside, Arsenal. Alexis Sánchez tries a through ball, but Mesut Özil is caught offside.
Own Goal by Robert Huth, Leicester City. Arsenal 1, Leicester City 0.
Attempt missed. Nacho Monreal (Arsenal) left footed shot from the left side of the box misses to the right. Assisted by Mesut Özil.
Offside, Leicester City. Kasper Schmeichel tries a through ball, but Shinji Okazaki is caught offside.