Rio Ferdinand is backing Dimitar Berbatov to finish the Italian job if Wayne Rooney fails to make United's Champions League tie with AC Milan at Old Trafford on Wednesday. United boss Sir Alex Ferguson says his leading scorer is "very doubtful" for David Beckham's eagerly-awaited return with Milan for the last-16 second leg encounter. Rooney's sore knee - aggravated playing for England at Wembley against Egypt last week - cost him his place against Wolves on Saturday. His two goals in the San Siro in the first leg have set United up with a 3-2 advantage and Ferguson's medical report could be a Euro bluff but, if not, Ferdinand believes Berbatov's display in the frontman role against Wolves is a plus for the Reds. "I wasn't surprised by his work-rate against Wolves. To be honest, if you look at the statistics you'll see that he's one of the hardest runners in our team," said Ferdinand. "He covers the most ground. He's a bit languid but he really puts the effort in. If you see him at the training ground, he's always in the gym. It's just his style of play. "People see a different side to him but I don't think that it actually reflects his importance to the team. He's appreciated by us and that's the most important thing. "I thought he was brilliant at Wolves. For one player to play up front on his own and occupy their back four the way he did was testament to his quality. If we win the league this year, I think he will be appreciated for what he has done." Ferdinand returned to United's defence after missing the West Ham league match and Carling Cup final against Villa with a minor recurrence of his back problem that cost him 19 matches earlier in the season. The twinge also forced the new England captain out of the Wembley friendly with Egypt. "I don't think about my role with England. I think about playing for United. My football is here at the moment," he said. "Everything else will click into place if I'm playing here. That's the only way I look at it." Do you think United will beat Milan without Rooney in the team? Have your say.