Arsenal boss Mikel Arteta was pleased with supersub Leandro Trossard after their 2-2 draw at Chelsea.
The Gunners fought back from 2-0 down to earn the point thanks to Trossard's late equaliser.
Arteta said: "First of all, he's very good. He's got this mentality to always be willing to help the team. He had an injury where he wasn't fit enough to play the last few games, then he played against City.
"He worked really hard across the international break to be able to be fit again. Those things - like with Martinelli - they change the momentum of the season. I could see he was ready to come in. It was a very intelligent run.
"The way he anticipates the action, it's easy to score."