Arsenal must come from behind to reach the Champions League final after Ousmane Dembele's early strike gave Paris St-Germain victory at Emirates Stadium.
Dembele stunned Arsenal when he swept home a low finish from Khvicha Kvaratskhelia's delivery only four minutes into the semi-final first leg.
PSG dominated the early stages with a relentless attacking assault, which saw Arsenal keeper David Raya make a superb save from teenager Desire Doue.
The hosts survived without further damage to work their way into contention, and once again giant Italian keeper Gianluigi Donnarumma, as he was against Liverpool and Aston Villa earlier in the competition, was PSG's hero.
He saved brilliantly from Gabriel Martinelli and Leandro Trossard either side of the break, while Arsenal saw Mikel Merino's header from a Declan Rice free-kick ruled out for offside.
PSG had chances to extend their advantage late on, but substitute Bradley Barcola shot wide and Goncalo Ramos hit the bar.
Arsenal's night of frustration
The hosts whipped the Emirates crowd into a frenzy with a spectacular light and pyrotechnics show before kick-off, only to see the thunderous atmosphere punctured almost immediately by that priceless early goal.
Mikel Arteta's side appeared to be stunned and could have suffered further damage as PSG poured forward in wave after wave of attacks in the opening phase.
Arsenal never lacked for heart or effort, but PSG controlled Bukayo Saka superbly and when the chances came they ran into the same wall of defiance from keeper Donnarumma that broke Liverpool and Aston Villa's hearts.
The Italy goalkeeper was the hero against Liverpool when PSG won on penalties at Anfield, while three superb second-half saves kept Unai Emery's side at bay at Villa Park.
Martinelli should have scored when clean through, but Donnarumma's low save diving to his left from Trossard was high class.
And when the Gunners thought they had made the breakthrough early in the second half, Merino's smart header was ruled out for offside after a lengthy video assistant referee check, although the very deep starting position of Arsenal's players at the set-piece was running that risk.
Arteta will believe his side can turn the tie around after beating Real Madrid at the Bernabeu, but PSG are an entirely different proposition and this now looks like a mammoth task for Arsenal reach the final in Munich.
