Old Trafford club are rumoured to be front-runners in the race to capture the Japanese star's signature this summer, and the Scottish boss is in attendance at the German cup final
Goal.com exclusively revealed in April that the current Premier League champions were lining up a bid to take the Japanese attacker to England, and Dortmund have hinted recently that the 23-year-old would be heading for the exit this summer.
Kagawa's contract expires in a little over a year, and Dortmund have stated that he will not sign an extension to his current deal, so are likely to cash in on their talented youngster this summer.
The Japanese midfielder arrived in Germany after the 2010 World Cup for a fee well below £1 million, and is expected to fetch upwards of £10m this year.
He has scored nine times in 29 international appearances for Japan, and has now scored 22 times in 50 appearances for the German club, including his opener in the cup final, after which Arjen Robben equalised from the penalty spot.