Wales have suffered a huge blow ahead of Saturday's clash against South Africa after Gavin Henson ruled himself out with an Achilles tendon problem.
Tom Shanklin joins Jamie Roberts at centre with Andrew Bishop on the bench.
Wales backs coach Robert Howley said: "Gavin told us that he's mentally and physically not ready.
"We left that decision to Gavin Henson and we feel he is a mature person and Gavin decided to make that decision to make himself unavailable to play."
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Howley said: "We hope the situation with Gavin will get better. He aggravated the injury on Sunday, six days ahead of the international.
"I think the fact he played on a football surface six days before the game didn't help.
"A six-day turnaround is a high demand on players and Gavin Henson has fallen foul of that."
Henson trained on Tuesday morning but not in the afternoon, and the same pattern was repeated on Thursday as Wales sought to nurse him through the problem.
"Gavin had taken part in training sessions on Tuesday and Thursday, but has also been rested for some of our sessions this week," Howley added.
"We have had ample opportunity to run the Shanklin and Roberts combination and knew this configuration would be our other option, but thought it was important that Gavin made the decision on his capability to play himself."
An ankle injury that needed surgery ruled Henson out of Wales' tour to South Africa in the summer and he has started only three Ospreys games this season after first appearing as a replacement against Ulster on 27 September.
He was also hit by a two-match ban for skipping Ospreys training, further limiting his game time in the build-up to the autumn Tests that kick off against the world champion Springboks.
Wales: Lee Byrne (Ospreys); Leigh Halfpenny (Cardiff Blues), Tom Shanklin (Cardiff Blues), Jamie Roberts (Cardiff Blues), Shane Williams (Ospreys); Stephen Jones (Scarlets), Gareth Cooper (Gloucester); Gethin Jenkins (Cardiff Blues), Matthew Rees (Scarlets), Adam Jones (Ospreys), Alun Wyn Jones (Ospreys), Ian Evans (Ospreys), Ryan Jones (Ospreys, capt), Martyn Williams (Cardiff Blues), Andy Powell (Cardiff Blues).
Replacements: Richard Hibbard (Ospreys), Duncan Jones (Ospreys), Ian Gough (Ospreys), Dafydd Jones (Scarlets), Dwayne Peel (Sale Sharks), James Hook (Ospreys), Andrew Bishop (Ospreys).
South Africa team: Conrad Jantjes; JP Pietersen, Adrian Jacobs; Jean de Villiers, Bryan Habana, Ruan Pienaar, Fourie du Preez; Tendai Mtawarira, Bismarck du Plessis, John Smit (capt), Bakkies Botha, Victor Matfield, Schalk Burger, Juan Smith, Pierre Spies.
Replacements: Brian Mujati, Gurthrö Steenkamp, Andries Bekker, Ryan Kankowski, Ricky Januarie, Frans Steyn, Jaque Fourie.
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