Wasps flanker Jack Willis could be out of action for up to 12 months because of the knee injury he sustained in Saturday's Premiership semi-final.
The 21-year-old had been named in England's squad for the tour of South Africa but now faces a lengthy absence.
Scans revealed he has injured several ligaments, including a rupture of the anterior cruciate ligament (ACL).
Willis went off after a collision towards the end of the first half with Saracens fly-half Owen Farrell.
A Wasps statement said: "Following consultation with a specialist, it has been determined that Jack Willis sustained a significant multi-ligament injury to his right knee during last Saturday's Aviva Premiership semi-final.
"The injury is expected to keep him out of action for a period between nine and 12 months."
The injury happened on Saracens' 4G pitch at Allianz Park, and although there has been no complaints from Wasps about it, former England winger Ugo Monye believes the nature of an artificial surface may have contributed.
Monye told BBC Radio 5 live's Rugby Union Weekly podcast: "I've played on 4G pitches a lot and I personally don't like it - it's a really hard surface.
"At the time you feel quick but it's putting so much extra pressure through your joints and when you're a big lad like Jack [who is 6ft 3in and weighs nearly 17 stone], you can see it.
"It was fairly innocuous - he just gets hit, his studs get trapped in the ground and unfortunately the ground wasn't going to move so it had to be his knee."
Meanwhile, defence coach Phil Blake has left Wasps at the end of his contract.
The Australian, 54, spent two seasons with the Coventry-based club.
"With Ian Costello and Danny Wilson joining Lee (Blackett) and Andy (Titterell), we clearly have more coaching resource available for next season," said director of rugby Dai Young.
"Ian has a lot of defence coaching experience from his time with Munster, so he will take the lead for us in this area."