Sir Alex Ferguson was hit by a double injury blow on Sunday as Ashley Young and Nemanja Vidic both limped off during Manchester United's 2-1 victory over Liverpool.
Vidic clashed heads with Reds defenders Andre Wisdom in the second half, falling heavily onto his knee. The Serbian international was taken off 10 minutes from time, and replaced by Chris Smalling, but United face an anxious wait to find out the severity of his injury.
Vidic has been plagued by injury troubles in recent years, with two serious knee problems in the past 13 months. The visit of Liverpool was only Vidic's fourth match since returning from his last injury. Ferguson's defensive problems could be compounded by the absence of Jonny Evans - the Northern Irishman missed the match against Liverpool with a hamstring problem.
Ashley Young also limped off after a tough tackle from Daniel Agger in the first-half. The England international carried on for 15 minutes but didn't return for the second half, and was replaced by Antonio Valencia.
The winger has missed a significant portion of the season already with a knee injury, and United fear he could have aggravated the complaint on Sunday.
The Daily Mail report that United are waiting to find out the severity of the injuries, but fear both could miss the next few matches.
The pair are sure to miss United's FA Cup replay with West Ham on Wednesday, according to the report, and could also be ruled out of next Sunday's trip to White Hart Lane to face Tottenham.