Arsenal beaten by Paris St Germain to dent Champions League final hopes .

Arsenal's Champions League aspirations were dashed after Ousmane Dembele fired Paris St Germain to a 1-0 victory in the first leg of their semi-final at the Emirates.

Dembele opened the scoring after four minutes, but Arsenal had a second-half goal disallowed as VAR ruled Mikel Merino's header from Declan Rice's free-kick was offside.

Goncalo Ramos, a PSG replacement, struck the Arsenal crossbar in the last moments. Mikel Arteta's players must now overcome a deficit in Paris next week to reach their first final in almost two decades.

Arteta demanded the best atmosphere the Emirates had ever generated, but the home fans were stunned into silence with only three minutes and 17 seconds on the clock.

Dembele, who was fired by Luis Enrique after Arsenal's comfortable 2-0 league stage victory over PSG in October, was the architect. The France international picked up the ball in the center of the pitch and was allowed to run uncontested before passing it to Khvicha Kvaratskhelia.

Dembele retrieved the rebound ball on the edge of Arsenal's penalty area and struck a left-footed shot into the turf and into the net off David Raya's post.

It was a dreadful start for Arsenal, who then spent the next 20 minutes chasing PSG shadows.

Kvaratskhelia requested a penalty when Jurrien Timber placed his left arm across the PSG winger's midriff, but his plea was denied. Kvaratskhelia was at it again moments later, when he had a shot at goal that deflected off Timber's studs, and Raya responded superbly.

Arsene Wenger, who led Arsenal to the competition's final 19 years ago, sat in the director's box with Prime Minister Sir Keir Starmer, looking pained. An impassioned Arteta became increasingly irritated with his team, who were so controlled against Real Madrid in the quarterfinals but so careless here.

Desire Doue came close to extending PSG's lead on the half-hour mark, but Raya made a wonderful one-handed save. Arsenal were struggling and were without the suspended Thomas Partey in the heart of their midfield.

However, they came alive in the final stages of the first period, with Joao Neves disposing of Merino as the Spaniard was about to pull the trigger.

On the stroke of half-time, Gabriel Martinelli found himself one-on-one with Gianluigi Donnarumma, but the PSG goalkeeper kept his team ahead with an excellent diving stop. Martinelli may have performed better, but he could also have been offside when he received the ball.

Arsenal needed a good start to the second half, and they felt they had equalized barely 90 seconds in when Merino headed in Declan Rice's free kick. However, VAR intervened, leaving Merino half a body width offside.

Rice, who was magnificent against Real Madrid but quiet on the night in a deeper role, broke past the defense and found Trossard.

Trossard had a shot at the PSG goal from the angle, but Donnarumma made another excellent stop to retain the French ahead. That was the best Arteta's side could hope for.

Arsenal had more possession, but they appeared to be out of ideas, while PSG was satisfied to maintain their lead.

With 10 minutes remaining, substitute Bradley Barcola nearly added a second, but his shot went barely wide before Ramos hit Raya's woodwork.

Arsenal pressed for an equaliser, but it never seemed to arrive, and they will travel to the Parc des Princes in just eight days trailing in the tie.