Arsenal star Theo Walcott says they must produce their best performance of the season if they're to beat Champions League semifinal opponents Manchester United.

"It was difficult to get into the game. A lot of our attacking players could say that," the England winger said. "We didn't create any chances and it will need our best performance of the season on Tuesday to go through to the final.

"Everyone was down after the first leg because we lost the game and didn't get the away goal we wanted.

"But, considering the number of chances they had, I think we got away with it.

"We would have taken a 1-0 defeat before the game, especially in view of Manuel Almunia's unbelievable performance."

Walcott maintains the Gunners are ready for the challenge.

"Now we're all buzzing and we have to believe that we can do it," he said. "It's the biggest game of our careers on our own pitch, in front of our own fans. That will be crucial - and we can't wait to get going."