Gabriel Martinelli and Leandro Trossard came off the bench to score as Arsenal began their Champions League campaign with a 2-0 win over Athletic Club in Bilbao.
The Gunners struggled to create clear chances for much of the contest until Mikel Arteta substituted summer signings Viktor Gyökeres and Eberechi Eze.
Martinelli latched onto a ball over the top from Trossard in the 72nd minute to score the breakthrough goal just 36 seconds after coming on.
The Brazilian forward then returned the favour for Trossard soon after to seal the victory.
The result means Arsenal have three points on the board already.
They have also conceded only one goal so far this season and will host Manchester City next.