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 Gyokeres 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.