Lewis was a canddiate for a place on Wales' summer tour

Highly-rated Ospreys open-side flanker Ben Lewis has been ruled out for up to six months with a right knee injury.

The 21-year-old academy product is set to undergo surgery on his anterior cruciate ligament on the weekend.

"The medical experts have recommended this in order to offset further degenerative damage in the future," said Ospreys physio Chris Towers.

Lewis was a candidate for Wales' South Africa tour after injuries to Martyn Williams and Robin Sowden-Taylor.

606: DEBATE How big a blow is Lewis' injury?

Colin Charvis, Richard Parks and Gavin Thomas will now be seen as the leading contenders for the vacant Wales number seven jersey on the two-Test June trip.

Lee Byrne, Dwayne Peel, Gavin Henson and Mike Phillips have also been ruled out by injury, and Alix Popham has made himself unavailable.