Manchester United boss Sir Alex Ferguson says he had been following Shinji Kagawa for over two years before signing him from Borussia Dortmund.

It was his second season, Sir Alex told ManUtd.com, that cemented the United manager's belief that Kagawa had the necessary attributes to succeed at Old Trafford.

"There was a lot of interest in him after his first season because he started so well at Dortmund," the United boss said.

"But I never think you can tell after one season. I wanted to see how he'd do in his second campaign - it's more of a test because your opponents tend to know more about you.

"He passed with flying colours. He was even better, in fact. So that was a straightforward decision for us."

Ferguson added: "Shinji's intelligent, fast, has quick feet and works very hard.

"At 23 he's a good age and already has a couple of years' experience at a big club in Borussia Dortmund.

"It's obvious he's a very good player. We have high hopes for him."