French international Paul Pogba could be out of action for three months, the Sunday Times reported on Sunday, dealing a huge blow to Manchester United.
The hamstring injury suffered by the 24-year-old -- an £89.3 million ($121 million, 105 million euros) signing from Juventus last year -- after just 18 minutes in Tuesday's Champions League match with Basel is worse than was thought originally according to a club source.
The source said he faced sitting on the sidelines of anything from six to 12 weeks.
"The injury is really bad," a United source was quoted as saying by the newspaper.
However, the club believe Pogba's injury was a result of the player overdoing his personal training outside of the club's supervision.
"It's not normal for a player respecting our training programme," the source said.
According to the newspaper, Pogba is keen to go to the United States to undergo treatment and rehabilitation with a group of personal trainers he used while on holiday there in the close season.
Should United's worst fears be realised Pogba would miss five Champions League games plus Premier League meetings with Liverpool, Tottenham Hotspur, Chelsea, Arsenal and Manchester City.