Sheridan is being treated for a back strain and he has not been involved for the Lions since last week’s hard-fought victory over the Southern Kings in Port Elizabeth.

With Scotland international Euan Murray out of the tour due to an ankle injury, Lions boss Ian McGeechan has summoned front-row reinforcements in England’s Tim Payne and Ireland tighthead John Hayes.

Both players start against the Emerging Springboks tomorrow, with Phil Vickery - who was destroyed by South Africa loosehead Tendai ‘The Beast’ Mtawarira in Durban two days ago and substituted after just 45 minutes - on replacement duty.

It leaves the door open for man-mountain Sheridan to make the Test 22, probably as bench cover for likely starters Gethin Jenkins and Adam Jones in an all-Wales front-row alongside hooker Matthew Rees.

“The medics are working on Andrew Sheridan, hopefully to have him fit for a full training session on Thursday,” said McGeechan.