Rooney completed his move to Old Trafford yesterday just before the transfer deadline and England Head Coach Eriksson can’t wait to get him back into international football.

Rooney is still recovering from a broken foot of course and is not included in the squad to face Austria and Poland in crucial World Cup qualifiers over the next week.

But Eriksson still couldn’t hide his glee at the thought of Rooney returning to action in time for matches against Wales and Azerbaijan in October.

He said: "I’m sorry for him and for England that’s he’s injured right now because what he showed in Portugal was absolutely fantastic.

"If he plays like he did in Portugal then you have to say he is world class, absolutely. I can say that he’s number one, the best. Maybe he is or he is not but he is among them that is for sure."

That is undoubtedly exactly what Manchester United manager Sir Alex Ferguson wanted to hear after making Rooney the most expensive teenager in English footballing history.

The fee for the former Everton man could rise to £27m if he is successful at Old Trafford - and the good news for both United and England is that Eriksson believes the youngster has a big, big future ahead of him.

He said: "I have been asked how much Wayne Rooney can improve and it’s a good question. But normally if you are only 18 then you will become much better in the future. I’m sure he will. Let us hope!

"Hearing the figures they talk about for his signing, £25m or something like that, it’s proof that he is a great player of course.

"Somebody asked me recently why is he so good. And one of the things I said was that he’s very cool out there on the pitch. I realised it the first time when we played a qualification game against Turkey at home.

"I told him in the morning he was going to start. For an 18 year old boy to start against Turkey in a qualification game should scare everyone. But it didn’t scare him at all! "OK," he said. That’s it - that’s all!

"In that situation you show you are cold - you are not worried, you are very confident about your own skill and that’s very good.

"I had Roberto Baggio at the same age and he was also very confident but I think Rooney is even more confident."

Of course Sven is not the only admirer of Rooney, who became a national hero in Euro 2004 and was courted by some of the biggest clubs in Europe.

He won fans across the globe with his performances in Portugal and is one of the most talked about players in world football.

His every move on the pitch is likely to be scrutinised this season, and his move to Old Trafford will only make the spotlight even brighter.

But the good news for Rooney fans - and for England - is that his national boss is certain he can cope.

"I have no worries so far that he will cope," said Sven. "He’s never showed that he is nervous or worried about anything.

"I think he will always be a guy who keeps his feet on the ground. Give him a ball and things will happen, that’s all he wants."