Arsenal came from behind to keep their hopes of qualifying for the Champions League alive as Lukas Podolski's double inspired a vital 3-1 win over West Ham on Tuesday.
Arsene Wenger's side are in danger of failing to reach Europe's elite club competition for the first time in 17 years after a miserable run saw them surrender fourth place to Everton.
The Gunners needed a victory over their London rivals to climb back into fourth, but their European bid looked in dire straits when Matthew Jarvis struck for the visitors late in the first half at the Emirates Stadium.
That shock revitalised a previously lethargic Arsenal and German forward Podolski equalised minutes later before France striker Olivier Giroud put them ahead soon after the interval.
Podolski's second in the closing stages sealed Arsenal's first victory in their last five league games and lifted the north Londoners one point clear of Everton, although Roberto Martinez's men are still in pole position as they will reclaim fourth place if they draw or win at home to Crystal Palace on Wednesday.
"We were under absolute pressure to win the game and after giving a lot on Saturday it was difficult," Wenger said.
"I was satisfied with the mental response of the team. We showed maturity not to panic when we went 1-0 down.
"The vital thing was to come back to 1-1 before halftime. It was a hard-fought and very enjoyable win."
Hammers boss Sam Allardyce added: "We worked really hard to get 1-0 up, but if you gift them two goals it's difficult to get a result. The defending for the second goal was pathetic."