Double Heineken cup winners Leicester Tigers could be without Fijian star Seru Rabeni for six weeks after he suffered a recurrence of his knee injury in the 50-7 win over Worcester on Monday.
The news means Rabeni may miss the two crucial Pool matches the Tigers have in their quest for quarter-final qualification.
Rabeni made his return against Worcester after a six-week lay-off only to injure the same knee after just 12 minutes of the game against the Warriors.
Rabeni damaged his knee for the first time against Worcester on November 13 and head coach John Wells does not expect him to be in action for over a month.
"It would appear that it could be a six-week affair; Seru's aggravated the same knee he injured some time ago," said Wells.
"It was quite innocuous, we've watched it in slow-motion, on video, and it appears as if he made contact with one of the Worcester lads in mid-air.
"There's nothing else to say about it really; if he's back before then, good, if not, the worst-case scenario is six weeks.
"Seru has no ACL (joint) on that particular knee, so his knee has reduced stability in any event.
"He's had a number of injuries since joining us, but he's been able to manage them, until, all of a sudden, his body broke down so to speak.
"He came back and despite training well something quite innocent happened. It could easily have happened to anybody else, it just happened to a guy on his weak knee."