"He passed with flying colours. He was even better, in fact. So that was a straightforward decision for us."
Kagawa has certainly impressed team-mates in training, while fans have also been quick to praise the attacker following his Tour 2012 performances.
His ability to use both feet, vision in the final third and direct running at opposition defences have added an extra dimension to the Reds' attack.
"Shinji's intelligent, fast, has quick feet and works very hard," Sir Alex said. "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."