Theo Walcott insists Arsenal maintain the self-belief they can upset Barcelona at the Nou Camp.

Despite Arsenal's injury problems - with Alex Song joining captain Cesc Fabregas, Andrey Arshavin, William Gallas and Robin van Persie on the sidelines - Walcott insists Arsene Wenger's men must keep the faith.

"We have got to believe we can come here and get a result, there is no point playing within ourselves, we have all got to be at it," he said.

"There are some big players missing, but players will come in and do a job.

"We just have to work 100%, that is all we can do."

Walcott added: "Barcelona played some fantastic football at times in the first half last week, and was some of the best I have even seen a team play.

"However, they seemed to die off a bit in the last 20 minutes and if we can keep it 0-0, or sneak an early goal hopefully we can upset the fans, keep them all quiet.

"We have scored a lot of late goals this season, especially in the Premier League, so hopefully we can believe and can do it again."