Arsenal 1, Swansea 2
Arsenal manager Arsene Wenger banned title talk after his team's Premier League challenge crumbled further with a dispiriting defeat to struggling Swansea.
The Gunners missed a huge chance to close the gap on leaders Leicester and rivals Tottenham — ahead of Saturday's north London derby — despite winger Joel Campbell putting them in front.
Former Spurs man Wayne Routledge equalised and Swansea captain Ashley Williams bundled in the winner after a flap from goalkeeper Petr Cech, who compounded Arsenal's misery by picking up a calf injury that rules him out of the trip to White Hart Lane.
"At the moment we don't dream, we have to be realistic and come back to what we do well, to the basics," said Wenger.
"We want to focus on winning the next game and not to talk about the title tonight. I am not in the mood. It's a big disappointment for us and we have to swallow that and bounce back."
Arsenal lie six points behind Leicester and three adrift of Tottenham. They have lost three games in a row in all competitions for the first time since April 2010. A fourth could finish their title hopes for good.
Campbell hooked a half-volley past Lukasz Fabianski to put Arsenal ahead in the 15th minute but Routledge soon equalised when he glided through a comatose Gunners defence, gathered Jack Cork's pass and slotted past Cech.
Striker Olivier Giroud, now goal-less in nine games, thundered a volley against the bar and Sanchez did likewise with a free-kick but Swansea nicked a first win in five when Cech palmed Gylfi Sigurdsson's free-kick into the onrushing Williams.