Gareth Davies will captain Wales against the Reds after Cory Hill's late withdrawal moments before kick-off for personal reasons.
Former St Helens star handed chance in Australia tour finale.
Grace scored 89 tries for St Helens in his league career.
Wales head out to Australia this week for a tour which takes in two Tests against the Wallabies and a meeting with the Queensland Reds.
Warren Gatland has confirmed his 34-player Wales squad that will leave for Australia on June 26 ahead of a two-Test series against the Wallabies.
Wales player ratings: Warren Gatland's Wales were brave but just didn't have the firepower to live with the Springboks after a yellow card filled opening quarter.
With a raft of injuries and unavailable players Wales are depleted against South Africa and will travel to Australia in hope rather than expectation
The Welsh Rugby Union announced that Morgan has been released from the squad to face South Africa and Australia.
Cardiff back row James Botham has been drafted into Warren Gatland's Wales squad ahead of their encounter with world champions South Africa at Twickenham on Saturday.