Match ends, Leicester City 2, Arsenal 5.
Arsenal forward Alexis Sanchez rediscovered his goalscoring touch as his hat-trick ended Leicester's unbeaten start to the season.
Jamie Vardy had put the Foxes ahead with a superb finish from a tight angle after a clinical counter attack.
Theo Walcott equalised when Leicester were themselves caught on the break.
Sanchez then took control of the contest with his treble - the pick his third from long range - as Vardy and Olivier Giroud netted late on.
Sanchez, who scored 25 goals last season for the Gunners, had failed to find the net in eight games across all competitions before this contest.
The result means Leicester are now without a win against Arsenal in 18 Premier League games, stretching back to November 1994.
Sanchez finding his stride
Following a relatively subdued start to the season, Sanchez showed his quality at the King Power Stadium.
He scored his first goal of the term with a poacher's effort when he tapped in from close range after good work down the right by Hector Bellerin.
From the moment the ball hit the back of the net the former Barcelona forward's confidence came flooding back.
He appeared in dangerous areas, ran at defenders and it was inevitable he would add to his tally later in the game.
Sanchez claimed his second with a header, with his hat-trick the pick of his three goals as he struck a low, powerful shot past Leicester goalkeeper Kasper Schmeichel.
Ranieri must plug leaky defence
Leicester have ridden their luck somewhat in their impressive start to the season, and against one of last term's top four it ran out.
Even when they were winning games Leicester boss Claudio Ranieri was complaining about how his side must learn to keep clean sheets.
The erudite Italian recently turned to offering pizza as an incentive for his players to increase their number of shut outs.
His culinary offerings make quirky headlines but extra time on the training ground is what is required to improve Leicester's leaky defence.
Failure to do so and Leicester will find themselves sliding down the table if the goals dry up at the other end.
Arsenal finally showing their true colours
Arsenal made an underwhelming start to the campaign - collecting four points from their first three games - which saw them written off as possible challengers to Manchester City and Chelsea.
But the Gunners completed their victory over Leicester in plenty of style. Back was the attractive one-touch football as they cut through Leicester's back line - albeit one that has now leaked 14 goals.
Arsenal manager Arsene Wenger said Sanchez is now "back to his best", and his side have now moved up to fourth in the table, just three points behind new leaders Manchester United.
Man of the match - Alexis Sanchez
Leicester boss Claudio Ranieri: "We must begin again now and repeat this start to the season. We fought and tried everything to score and the match was very open in the first half, but in the second half when Sanchez scored it was finished."
Arsenal manager Arsene Wenger: "It took Alexis a while to find his form. He didn't come back straight away from the Copa America and after a competition like that it takes some time. Alexis was waiting for a goal and he's not used to not scoring for so long so it was important for him to score."
The stats you need to know
- Alexis Sanchez is the first player to score hat-tricks in the Premier League, Serie A and La Liga
- Theo Walcott has netted 12 goals in his last 13 Premier League starts
- Since making his Premier League debut in August 2012, Santi Cazorla has provided more assists than any other player (32).
- Jamie Vardy has scored in four successive league games for the first time in his career.
- Only once in their 19 league meetings have Arsenal failed to score against Leicester.
- Arsenal netted five goals against Leicester, as many as they had scored in their previous six top-tier games in total.
Arsenal host Greek side Olympiakos in the Champions League on Tuesday (19:45 BST) while Leicester travel to Norwich next Saturday (15:00).
- 2de Laet
- 4DrinkwaterBooked at 72minsSubstituted forKramaricat 78'minutes
- 11AlbrightonSubstituted forUlloaat 64'minutes
- 20OkazakiSubstituted forKingat 45'minutes
- 20FlaminiSubstituted forArtetaat 21'minutesBooked at 68mins
- 16RamseySubstituted forOxlade-Chamberlainat 77'minutes
- 14WalcottSubstituted forGiroudat 80'minutes
- Craig Pawson
- Shots on Target
Second Half ends, Leicester City 2, Arsenal 5.
Goal! Leicester City 2, Arsenal 5. Olivier Giroud (Arsenal) left footed shot from the centre of the box to the bottom left corner. Assisted by Nacho Monreal with a cross.
Mikel Arteta (Arsenal) wins a free kick in the attacking half.
Foul by Leonardo Ulloa (Leicester City).
Mikel Arteta (Arsenal) wins a free kick in the defensive half.
Foul by Andrej Kramaric (Leicester City).
Attempt saved. Mesut Özil (Arsenal) left footed shot from the left side of the box is saved in the bottom right corner. Assisted by Alex Oxlade-Chamberlain.
Goal! Leicester City 2, Arsenal 4. Jamie Vardy (Leicester City) right footed shot from the left side of the box to the bottom right corner. Assisted by Leonardo Ulloa.
Attempt saved. Andrej Kramaric (Leicester City) right footed shot from the centre of the box is saved in the bottom left corner. Assisted by Riyad Mahrez with a cross.
Attempt blocked. Riyad Mahrez (Leicester City) right footed shot from the right side of the box is blocked. Assisted by Jamie Vardy with a cross.
Alex Oxlade-Chamberlain (Arsenal) wins a free kick on the right wing.
Foul by N'Golo Kanté (Leicester City).
Attempt missed. Wes Morgan (Leicester City) header from the left side of the six yard box misses to the left. Assisted by Riyad Mahrez with a cross following a corner.
Corner, Leicester City. Conceded by Per Mertesacker.
Corner, Leicester City. Conceded by Petr Cech.
Attempt saved. Riyad Mahrez (Leicester City) left footed shot from the left side of the box is saved in the bottom right corner. Assisted by Andrej Kramaric with a cross.
Corner, Leicester City. Conceded by Petr Cech.
Attempt saved. Jamie Vardy (Leicester City) left footed shot from the left side of the box is saved in the centre of the goal. Assisted by Kasper Schmeichel.
Goal! Leicester City 1, Arsenal 4. Alexis Sánchez (Arsenal) right footed shot from outside the box to the bottom left corner. Assisted by Nacho Monreal.