Manchester United are searching for an explanation after Shinji Kagawa publicly criticised David Moyes, reports the Metro.
Following an impressive display for his national side Japan, which was capped off with a fine goal, Kagawa aired his frustration at not getting enough playing time for Manchester United this season.
After the 3-1 against Ghana he was quoted as saying: "Please ask David Moyes why I’m not in the side.
"It is frustrating not playing but to score a goal like that gives me confidence. Hopefully I can take that back to my club with me and things will improve."
The comments have left management at Old Trafford bemused, as there was a belief that Kagawa and Moyes had an agreement to work him in to the squad gradually due to a lack of match sharpness.
Kagawa returned from international duty full of confidence after his performance against Ghana and is in line to play against Crystal Palace on Saturday.
Marouane Fellaini is also expected to deputise for the Premier League champions, in what will be an anticipated debut.