Stephen Jones is out of the Wales side to face England in the Lloyds TSB Six Nations match at Twickenham.
The Llanelli outside half has not recovered from the back spasms he suffered during the week and Iestyn Harris will take his place.
It will be the first time Harris has started a Lloyds TSB Six Nations match in his club position and he will be joined at half-back by his Cardiff partner Rob Howley.
Harris figured at centre in the opening championship match against Ireland and came on as a second half replacement full back against Italy.
Another Cardiff player, Nicky Robinson, has been brought onto the replacements bench to fill Harris' shirt. He was due to play for Wales Under 21 against England Under 21.
England have also had to make a change to their replacements. Sale Sharks outside half Charlie Hodgson has withdrawn through injury and Bath's Iain Balshaw has taken his place.
When the Wales squad were asked to nominate individuals who played a big part in their early playing days, Wales and Dragons full back and wing Hallam Amos thought of his former Monmouth School rugby coach John Bevan.
Sam Cross and Luke Treharne have been named as co-captains of the Wales Sevens side as head coach Gareth Williams names his 12-man squad to play in the first leg of the HSBC World Series in Dubai next weekend.
Bedwas head coach Steve Law and players Nicky Griffiths and Alun Rees extol the virtues of the close knit club as they prepare to host third place RGC 1404 - who are one place head of them on the Principality Premiership points table - on Saturday.
Many of the Wales squad have said Diolch (thank you) to someone who played an important part in their early playing days by nominating them to be invited to the Wales v South Africa match. One person, Gowerton Comprehensive geography teacher Mr Dean Mason was nominated by two of his former pupils, Dan Biggar and Sam Davies.
The second WRU disability rugby pilot has been delivered, this time in Caerphilly schools, culminating in a festival at the Caerphilly Centre of Sporting Excellence, Ystrad Mynach tomorrow. Plans are in place to set up a Disability Rugby Club in Newbridge to provide long-term playing opportunities.
WRU TV: Hear from inside the Wales camp as Neil Jenkins discusses this weekend's clash with South Africa and how the squad are looking to put in a strong performance to round of the 2016 Under Armour Series