Wasps flanker Jack Willis could be out for a year after suffering a serious knee injury during the Premiership semi-final defeat to Saracens.

Willis was helped off after doing damage late in the first half of a 57-33 victory for Sarries at Allianz Park.

The uncapped 21-year-old back-row was due to tour South Africa with England next month, but he now faces a long spell out of the game.

Wasps revealed in a statement: "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.

"This includes a rupture of his anterior cruciate ligament (ACL).

"The injury is expected to keep him out of action for a period between nine and 12 months."

Willis' injury setback will leave him little time to force his way into Eddie Jones' Rugby World Cup squad.