Ivan Toney scored a deserved equaliser as Brentford left Arsenal with a draw that could blow the Premier League title race wide open.
Leandro Trossard’s first Gunners goal had given them the lead in a game where they toiled for large periods, with Toney nodding in a leveller to earn a 1-1 draw and extend their unbeaten league run to 10 games.
Arsenal had lost at struggling Everton last week and could only follow that up with a share of the spoils here, leaving them six points clear of Manchester City.
Their main title rivals, though, host Aston Villa on Sunday before travelling to the Emirates Stadium on Wednesday for a game which could prove pivotal.
“Of course it's nice to have the goal as it gets me going but after that it's disappointing they got the equaliser,” Trossard told the BBC. “It's a tough one to take. We did everything well. To score against Brentford isn't easy.
“We said before on the set-pieces they're really good and today it happened again. We have to learn from that. There's a game again on Wednesday to turn things around.
“You don't get your way every game. We have to work hard every single day. There's a great atmosphere in the team and we have to keep that momentum going even when results don't go your way.”
Mikel Arteta stuck with the same starting XI that had been turned over at Goodison Park and they struggled for creativity as Brentford wasted a host of opportunities to take the lead.
The opening half-hour saw Arsenal labour in attack and struggle defensively, Rico Henry missing a fine early chance for Brentford before Bryan Mbeumo tucked home only to see his strike ruled out for the merest of shirt pulls.
Toney hit the crossbar when he should have broken the deadlock as the visitors started in the vein of a team on a nine-game unbeaten league run.
Brentford had plenty of men behind the ball, relying on their strikers when they could get forward as Toney worked Aaron Ramsdale with a strike from distance.
Arsenal’s first effort of note came just moments before the break, Granit Xhaka heading down a Ben White cross into the path of Gabriel Martinelli, who could only fizz a shot narrowly over the top.
The Gunners were sharper after the interval, Bukayo Saka and Martin Odegaard drawing saves out of David Raya as two of their shining lights of the campaign tried to stir the side from their collective slumber.
Brentford, though, still threatened and missed another gilt-edged chance to take the lead, Toney’s low effort flashing wide of the post having been picked out inside the box by Mathias Jensen.
Arteta went to his bench in search of the winning formula, January signing Trossard replacing the ineffectual Martinelli down the left-flank.
It took just four minutes for his decision to pay off, the Belgium international arriving unmarked at the back-post to turn home a fine Saka cross and open his Arsenal account with 66 minutes on the clock.
Still, though, Brentford were in the fight and levelled eight minutes after slipping behind as Toney headed home into an open net after Arsenal failed to deal with a free-kick into the box.
Like last week at Everton, Arsenal failed to create any meaningful chances in the closing stages and had to settle for a point, leaving them hopeful for a favour from former boss Unai Emery and his Villa side on Sunday.
Victory for City in that game would mean Pep Guardiola’s side would take over at the summit with three points in midweek as Arsenal’s title tilt faces a first true test.