Arsenal boss Arsene Wenger insists he was pleased with Theo Walcott's performance in yesterday's win over Wolves.
Walcott tended to drift in and out of the match.
But Wenger told arsenal.com: "It is difficult physically to run at the pace of a 100m runner and give always the right ball at that pace.
"Also, it is difficult for a player to make 100m races 50 times. He is not a player who makes a burst of just five yards, he is a player who every time runs 30 or 40 metres, that takes a lot out of you, and when it comes to the situation when you have to cross the ball, he already has a big effort behind him. I do not know yet if he will start against Barcelona, because I have to study what I have to do. I have tomorrow and Monday, so I will have to see."