Alves faces Ronaldo and Real Madrid tomorrow night in the El Clasico.
He told the Guardian: "I have a real weakness for Rooney he's incredible, incredible. He's fantastic.
"The way he works. He's perfect.
"He's better than Cristiano Ronaldo but Ronaldo took protagonism off him last year.
"Rooney was practically playing at left-back sometimes. The game that he played here against Barcelona in the Champions League, when Ronaldo missed the penalty, he was at left-back
"For us it's better - the further away he is from our goal the better. But for those who have a passion for football, it's a disaster.
"When you see a player that good with that quality stuck at left back, buf! But that's the thing: sometimes it's hard in a team to have lots of players with big names; sometimes they take something away from each other.
"Right now, maybe Manchester United play better as a team than before, when they had Ronaldo. They're as good, or better, as they were.
"But Rooney knows that his best position is up front - and he's proving that. He's got over 30 goals. It's incredible."