Arsenal missed the chance to close the gap on Manchester United in the race for Champions League qualification as they fell to a 2-1 defeat to Brighton at the Amex Stadium.
Bukayo Saka has been one of the Gunners' bright sparks this season and the 18-year-old demonstrated why with a wonderful curling effort crashing against the crossbar early on.
The winger then supplied a pinpoint cross to Lacazette, but the French striker couldn't sort out his feet in time to tuck home and Brighton scrambled clear.
Having lost Granit Xhaka and Pablo Mari to injury against Manchester City in midweek, Arsenal's crisis worsened when Bernd Leno suffered a potentially serious knee injury.
The German rushed off his line to collect a bouncing ball and collided with Neal Maupay, with the stopper's screams of agony eerily echoing around the Amex Stadium.
Leno was stretchered off and replaced by Emiliano Martinez, who was forced into a fine stop just minutes after coming on.
Aubameyang did get a rare sight of goal after a clever exchange with Alexandre Lacazette only to be denied by a superb last-ditch challenge from Aidan Webster.
After a slow start to the second half, Arsenal began to show their pace on the counter with Saka sliding in Aubameyang, who finished with aplomb but the offside flag was raised - and a VAR replay showed he was only a few inches shy of being onside.
Martinez had to be on hand to deny Maupay from point-blank range as both sides displayed their attacking threat. But an incisive breakaway from the visitors saw the deadlock broken after 67 minutes when Saka found Nicolas Pepe and the Ivorian struck a stunning curling effort into the top corner.
But Arsenal failed to build on their lead with Aubameyang twice denied and paid the price for some sloppy defending from a set piece when Lewis Dunk prodded home from close range after Brighton worked a short corner.
Arteta sent on Kieran Tierney, Joe Willock and Reiss Nelson late on in attempt to find a winner, but it was Maupay who scored deep into injury time to win the game.
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