The 26-year-old ruptured his anterior cruciate ligament in the recent pre-season game against Agen and has been ruled out for between six and nine months after undergoing surgery.
The injury is the latest in a long line of problems that have ravaged the England international's career to date and robs new Wasps boss Dai Young of one of his key players.
Young said: "The injury is a huge blow for Tom and everyone at Wasps. 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 was named club captain for the 2009-10 season but played only seven games after being forced to undergo surgery on a shoulder problem.
He also missed the second half of last term to have another shoulder reconstruction and will now not feature until well into the New Year.
Wasps will also be missing locks Dan Ward-Smith and Ross Filipo, flanker Joe Worsley and centre Dominic Waldouck when the new season gets under way on the first weekend in September.
Ward-Smith is seeking medical advice for an ongoing back problem while Worsley is doing likewise for a neck complaint.
Filipo is on his way back from a damaged knee cartilage and Waldouck is on course to return from an Achilles tear in October.
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