Wales fly-half Stephen Jones has pulled out of Saturday's clash with South Africa because of a thigh injury.
Jones, who had been named on the bench for the Millennium Stadium showdown against the world champions, is replaced by Ceri Sweeney.
The 29-year-old sustained the damage to his left thigh during Llanelli's 33-17 Heineken Cup defeat by Wasps last weekend.
Dragons fly-half Sweeney was a member of caretaker coach Nigel Davies' preliminary training squad.
Davies said: 'It's unfortunate we will not have Stephen's experience to rely on from the bench, but Ceri is a seasoned professional and will not let us down if called upon.
'He's probably the top kicker in Wales at the moment in terms of his accuracy and he can fit in at both fly-half and centre.
'With 34 caps to his name he has been an integral part of the Wales squad for some time and we'll have no hesitation in putting him on if necessary.
'His arrival in camp has had a positive impact already. He has an infectious personality and has been giving positive vibes to those around him all morning.'