Lewis, 21, faces an anterior cruciate ligament reconstruction.

He will become the fifth Ospreys player to have surgery this spring, following Mike Phillips, Gavin Henson, Lee Byrne and Andrew Millward.

Ospreys physiotherapist Chris Towers said: “The underlying ligament damage is a pre-existing condition which hasn’t prevented Ben from functioning at the highest level, despite being ACL-deficient.

“As part of our routine checks, we have picked up the start of some cartilage damage, which has developed as a direct result of the ligament laxity.

“In light of the fact that he is playing and training at the top level of professional rugby, the medical experts have recommended the reconstruction in order to stabilise the laxity and offset further degenerative damage in the future.”