Gareth Davies will captain Wales against the Reds after Cory Hill's late withdrawal moments before kick-off for personal reasons.
Grace scored 89 tries for St Helens in his league career.
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.
The ball-playing Ospreys loosehead is finding his voice as a leader he prepares to take on the fearsome Springboks pack
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.
Cardiff slumped to an eighth successive United Rugby Championship defeat after being dispatched 34-13 by the Lions in Johannesburg.
The Cardiff forward made his Wales breakthrough in time to earn selection in Warren Gatland’s squad for France.
Wales prop Corey Domachowski recalled “bittersweet” emotions after gaining World Cup selection on the same day as his great-grandmother’s funeral.
