Arsenal ended a seven-match Premier League winless run as they came from behind to beat West Ham 3-1 and give Freddie Ljungberg his first victory as interim head coach.
The sacking of Unai Emery had not yielded the expected upturn in fortunes most would have expected, with Ljungberg overseeing a 2-2 draw at Norwich City and a 2-1 home defeat to Brighton and Hove Albion in his first two games in charge.
It looked set to be another chastening evening for Ljungberg when Angelo Ogbonna put West Ham ahead in the 38th minute at London Stadium.
Arsenal's display had been limp and lifeless in the first half but Gabriel Martinelli's goal on his full Premier League debut sparked them into life.
A spectacular Nicolas Pepe strike made it 2-1 and Pierre-Emerick Aubameyang converted a cross from the former Lille star for the Gunners' third goal in the space of nine minutes, a blitz Manuel Pellegrini's struggling Hammers never recovered from.
The early omens for Arsenal were worrying as they lost Hector Bellerin to injury in the warm-up.
Ainsley Maitland-Niles took his place in the starting XI and, having been deprived of one full-back, the Gunners then saw another forced off as Kieran Tierney suffered a shoulder injury and was replaced by Sead Kolasinac.
There was further frustration for the visitors when Mesut Ozil headed over from point-blank range from Aubameyang's left-wing cross.
The impact of that miss was exacerbated as Ogbonna broke the deadlock.
Arsenal failed to clear a Snodgrass corner and Pablo Fornals whipped a right-wing delivery in for Ogbonna, whose effort deflected in off Maitland-Niles and was allowed to stand despite it appearing to come off his shoulder.
Ljungberg's men had offered little to suggest a fightback was on the cards but, against the run of play, they levelled matters as Martinelli got off the mark in the Premier League.
Kolasinac did excellently to pick out the Brazilian, who found the bottom-right corner with a confident first-time finish, and six minutes later the turnaround was completed in stunning fashion.
Pepe cut in from the right and bent an unstoppable strike into the far corner before then lofting a cross into the box for Aubameyang to fire an acrobatic strike into the ground and beyond David Martin, who, despite getting a hand to the ball, could not keep out a shot that proved the telling blow in the contest.