Eddie Nketiah enhanced Arsenal’s chances of finishing in the Premier League’s top four with a double against Chelsea on Wednesday.
Nketiah was released by Chelsea as a 16-year-old in 2015, and he has exacted some vengeance this season with his first league goals.
The 22-year-old opened the scoring for Arsenal at Stamford Bridge before Timo Werner leveled.
Mikel Arteta’s side reclaimed the lead through Emile Smith Rowe, only for Cesar Azpilicueta to equalize again for Chelsea.
Nketiah resolved a tense London derby in the second half when he punished Chelsea’s poor defending, and Bukayo Saka added a fourth with a stoppage-time penalty.
After losing their previous three games, Nketiah’s vital contribution propelled Arsenal back into contention for a top-four finish in the race to qualify for next season’s Champions League.
Arsenal sit fifth, one point behind fourth-placed Tottenham, with both teams having six games remaining.
Arsenal’s ambitions of qualifying for the Champions League for the first time since 2017 face another crucial test on Saturday when they go to sixth-placed Manchester United.
Finalists in the FA Cup Chelsea stay third, but are only five points clear of Arsenal and cannot take a top-four finish for granted.
Stamford Bridge was slightly less than capacity when the first round of ticket limitations, enforced by the British government’s sanctions against Roman Abramovich, took effect.
Those who were admitted were treated to an electrifying first half, with Romelu Lukaku’s woes continuing as the Chelsea striker scuffed a good early chance beyond.
Chelsea’s defending was incredibly unimpressive without Thiago Silva and Antonio Rudiger, and Arsenal took the lead in the 13th minute.
– Shambolic Chelsea – Andreas Christensen fumbled his back ball and, with Malang Sarr caught off guard, Nketiah was free to gallop clear and plant a composed finish beyond Edouard Mendy from the edge of the area.
Werner equalized for Chelsea four minutes later when Ruben Loftus-Cheek intercepted Nketiah’s pass and set up the German, whose 20-yard strike deflected off Granit Xhaka and looped over Aaron Ramsdale.
Chelsea were dealt a sucker punch in the 27th minute when Xhaka and Saka orchestrated a swift counter from a Blues corner, with Martin Odegaard setting up Smith Rowe for a low strike past Mendy.
Arsenal’s defense, on the other hand, was just as shaky as Chelsea’s, and the visitors conceded once more five minutes later.
Ben White’s appeals for a foul on Werner were dismissed, and Mason Mount sent an exquisite cross for Azpilicueta to tap home from close range.
Smith Rowe came within inches of restoring Arsenal’s advantage as he wriggled past three defenders and fired well wide.
At half-time, Tuchel substituted Silva for Christensen, but the Brazilian’s introduction had no effect on Chelsea’s shambolic defensive display.
Silva’s tackle redirected the ball towards Sarr and N’Golo Kante in the 57th minute, but neither reacted quickly enough to remove the danger before Nketiah pushed his effort beyond Mendy.
Lukaku has not scored in the Premier League since December’s victory against Brighton, with his only goals coming against less-than-impressive opposition in Chesterfield, Al Hilal, Palmeiras, Luton, and Middlesbrough.
Chelsea’s £97 million club record signing was once again relatively anonymous until he was replaced by Kai Havertz.
Marcos Alonso came close to equalising after Ramsdale mishandled Reece James’ cross, but his goalbound effort was blocked.
Saka sealed the victory with a clinical penalty conversion after Azpilicueta pulled down the Arsenal forward.
Chelsea had conceded 11 goals in their previous three home matches, and Azpilicueta’s fury erupted in a furious argument with a fan following the final whistle.