Marx, one of the Boks' outstanding performers this year, sat out of the game as a precautionary measure after he picked up a shoulder injury against France, while Kolisi went home for the birth of his second child and re-joined the squad on Sunday.
“Mtawarira sustained a groin injury in the second half of the Italian clash, which forced him off the field. He will be given as much time as he needs to recover,” team doctor Conrad von Hagen said on Monday.
Prop Thomas du Toit joined the squad on Monday as injury cover.
“We will be playing against a very good Welsh team with a fantastic coaching staff and experienced international players. We know we have to be at our best again this weekend to keep on with the improvement in our game,” coach Allister Coetzee told a news conference.
It is the last of four internationals for South Africa on their European tour which started with a heavy defeat in Ireland.
(Reporting by Mark Gleeson,; Editing by Ed Osmond)
