England and Wasps lock Joe Launchbury is out of contention for the British and Irish Lions' South Africa tour after suffering a serious knee injury.
Wasps say their captain sustained "a complete rupture" of his anterior cruciate ligament during Sunday's Gallagher Premiership victory over Bath.
The normal recovery period for such an injury is between six and nine months.
Launchbury, who has won 69 caps, missed England's Guinness Six Nations campaign this season because of a broken leg.
Lions head coach Warren Gatland is due to name his squad next week for this summer's tour, and 30-year-old Launchbury would undoubtedly have been part of second-row discussions.
In a statement, Wasps said: "Joe Launchbury sustained a complete rupture of his anterior cruciate ligament (ACL) during Sunday's game against Bath Rugby.
"He has had a consultation with a knee specialist, who has confirmed that he will require surgery.
"Everyone at Wasps wishes Joe all the best for a speedy recovery."