Rooney is out with an ankle injury that he suffered in the Champions League quarter-final first leg defeat against Bayern Munich.
“They’re not the same team without him,” said the Italian.
“Rooney is a fantastic player who is difficult to replace with another player. (Dimitar) Berbatov is good but Rooney is totally different.
“Rooney can sometimes come back to receive the ball and use it for all the team and then he can attack in any direction.
“He is an unbelievable player.”
“It is not a good moment for United after losing to Bayern during the week and because they have lost a very important player,” he added.
“It’s not easy for United to maintain their characteristic and momentum without Rooney.
“But they have the possibility to move on and I hope they get to the semi-final.”
