London Wasps flanker Tom Rees could miss the whole of the Aviva Premiership season with a knee injury.
The 26-year-old ruptured his anterior cruciate ligament during a recent pre-season friendly encounter with Agen and could be out of action for nine months.
"The injury is a huge blow for Tom and everyone at Wasps," said Wasps boss Dai Young.
"We all saw how incredibly hard Tom worked to get back to full fitness from last season's injury so this is desperately disappointing.
"As director of rugby, Tom was someone I had earmarked to have a major impact this season both on and off the pitch and he will be sorely missed. We all wish him the best in his recovery."
Rees has made 15 appearances for England.
