Manchester United striker Javier Hernandez will be out for up to four weeks after tearing ankle ligaments.
The Mexican forward, who has scored six league goals this season, suffered the injury in the early stages of United's 1-0 win at Aston Villa on Saturday.
"I think he's torn ligaments in his ankle," said manager Sir Alex Ferguson, whose side are five points behind Premier League leaders Manchester City.
"He'll be out for between three and four weeks."
Hernandez was one of three players forced off during the match at Villa Park, with Shay Given and Jermaine Jenas also picking up fairly innocuous injuries.
With Michael Owen and Dimitar Berbatov already ruled out until Christmas at least, it leaves Ferguson short up front.
He will, however, have been cheered by the return from injury of England international Danny Welbeck, who stepped from the bench at Villa Park.
"We're having a bad time with injuries at the moment," added Ferguson. "It's just as well we've a strong squad."
Brazilian twins Rafael and Fabio and midfielders Tom Cleverley and Anderson are also on the sidelines.
Villa manager Alex McLeish has worries of his own after goalkeeper Given and midfielder Jenas were both replaced during the match.
"I'm not sure but I think Shay had a little tweak in his hamstring. Hopefully it's a grade one [tear] and will heal really quickly," McLeish said.
"As for Jermaine, we don't know, but we think he's had an injury to his Achilles but we will wait until the morning to see."