Shinji Kagawa is a major doubt for Manchester United's Premier League match against Wigan on Saturday after sitting out Japan's World Cup qualifier against Iraq because of back pain.
The attacking midfielder felt pain in his lower back during a training session on Monday, ruling him out of his side's 1-0 win yesterday.
United are already without Wayne Rooney, who plays in a similar position, due to a gashed leg.
"I felt a twinge during training," Kagawa said. "It's not that serious and should not keep me out for long."