The Japanese midfielder was hooked by United boss David Moyes after just 45 minutes against West Brom, and admitted after the match that he needs to improve if he's to stake his claim for a regular starting spot.
But Le 10 Sport claims Atletico Madrid could renew their interest in the United star in the January transfer window in the hope of luring him away from the Premier League champions.
The La Liga side were linked with Kagawa over the summer, and the report suggests they may look to take advantage of his situation at United to swoop in the winter window again.
Following the surprise 2-1 defeat to the Baggies at Old Trafford on Saturday the Japan international admitted he's been disappointed with his performances for United so far.
Kagawa made 20 Premier League appearances for the Red Devils last season, scoring six goals - including a hat-trick against Norwich City - and providing three assists.
The former-Borussia Dortmund star has barely featured under David Moyes though, making his first Premier League start of the campaign against West Brom.