Arsenal kicked off their Champions League campaign in style on Tuesday, as two goals from substitutes Gabriel Martinelli and Leandro Trossard powered them to a 2-0 victory over Athletic Bilbao.

In a match that was goalless for over an hour, both players came off the bench in the second half to turn the tide.

The first half at San Mamés was a cautious affair, with both teams struggling to create clear opportunities. Bilbao had plenty of shots, but none tested the Arsenal goalkeeper, while the Gunners managed only one shot on target from striker Viktor Gyökeres, whose effort was easily saved.

Gyökeres later suffered a head injury in a collision but continued to play with a bandage.

Arsenal manager Mikel Arteta’s tactical changes proved to be the difference-maker. He introduced Trossard in the 65th minute for Gyökeres, and then Martinelli for Eberechi Eze six minutes later. The move paid off almost immediately.

Trossard initiated the first goal at 72nd minute with a clever flick to Martinelli, who then weaved past a defender before coolly slotting the ball into the net to give Arsenal the lead.

Just three minutes from time, the two reversed roles. Martinelli cut inside from the left and delivered a precise pass to Trossard, who fired a powerful strike between two defenders to seal the victory.

The late goals highlighted Arsenal's second-half resurgence, as they registered five shots on target in the final 45 minutes, while Bilbao failed to seriously threaten the visiting side's defense.

Last season, Arsenal started their campaign with a 0-0 draw with Atalanta. They nearly faced a similar outcome this time, but this time, Arteta’s tactical masterclass allowed them to defeat an Athletic side making their first Champions League appearance since 2014.

Arsenal will host Olympiakos in their next Champions League match on October 1, while Athletic Bilbao travels to face Borussia Dortmund on the same day.