STEVE McClaren has a stark warning for football managers across the world - the best of Wayne Rooney is still to come.

The Boro boss watched on as the 19-year-old ripped his FA Cup dreams apart with two sumptuous second half strikes at Old Trafford on Saturday.

"Everyone saw that talent at 16 and 17 and couldn't believe it," said McClaren, who has witnessed Rooney's qualities at first hand in his role as an England coach.

"What boundaries can you put on a player who's just 19, playing at Man United and playing at the level he is?

"He wants to play and he wants to learn. I saw his first game here when he scored a hat-trick (against Fenerbahce). That was an instant message that yes he could be a player everybody adores. What's he going to be like when he's 22 or 23? He just loves playing football."

Boro had no answer to Rooney and McClaren believes the striker is an even better player when opponents try to stop him playing.

McClaren said: "I think one of the things about Rooney is that it's very difficult to stop him. Physically he's very strong. He's very tough and he's a great competitor. Trying to stop him, he relishes the challenge.

"A lot of people talk about England in Portugal and when he went off against Portugal and how that was the defining moment. Who knows?

"As a footballer he can play anywhere. He's got the intelligence that he can play up front, second striker, he can play wide in a three and he can play midfield. When you've got that talent - what an asset."

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