United face Seedorf's AC Milan this week in the Champions League.
Rooney said: "For me, Seedorf is probably the best player I've ever played against," Wayne said recently. "When we played Milan at the San Siro a few years ago, he was unbelievable."
And on Milan's other threats, he added: "Milan have a number of players who can score goals, particularly from set-pieces, so I think we'll have to be wary of that.
"They have Pirlo and Becks some great players. Ronaldinho is a special player, too. He's unbelievable when he's on form. I saw recently that he was voted Player of the Decade, so that shows how much of a talent he is. We'll need to be at our best to beat them."