Charvis and his team-mates face the Springboks in a one-off Test at Loftus Versfeld in Pretoria on Saturday.

Wales have travelled to South Africa after a hard-fought Test series in Argentina, which ended 1-1.

South Africa are in a rebuilding phase under new coach Jake White but have already beaten Ireland twice this month and Charvis is anticipating a step up in intensity.

"When we go up against the Springboks, we'll have to play a much tougher brand of rugby for the whole game or we will be punished,'' said Charvis.

"We didn't play for the whole 80 minutes in either match in Argentina.

"We are going to have to perform for the full 80 this weekend, because it's going to be very tough against South Africa.

"They have shown against Ireland just how strong they are. If we let them start strongly against us then we are really going to have our work cut out.''

Charvis nevertheless has seen plenty of signs for encouragement in his side's recent performances and believes they are capable of upsetting the Springboks.

Wales were thrashed 96-3 on the same ground in 1998 but there would seem little chance of a repeat this time.

"The players are very enthusiastic about the challenge ahead and, if we get the right attitude, we can compete against the Springboks,'' he said.

"We are without a few key players on this trip, but we seem to be getting better and better and, hopefully, we can continue that progress.''

The Welsh pushed the Boks hard two years ago but there are still question marks over the ability of their pack to compete with the hosts' powerful forward unit and it will be difficult for them at altitude.

Wales will also need to watch discipline having picked up three yellow cards against the Pumas.

Wales team to face South Africa in Pretoria on Saturday: G Henson (Neath-Swansea); H Luscombe (Newport-Gwent), S Parker (Neath-Swansea), T Shanklin (Cardiff), S Williams (Neath-Swansea); N Robinson (Cardiff), D Peel (Llanelli); M Owen (Newport-Gwent), C Charvis (Newcastle, capt), Dafydd Jones (Llanelli), G Llewellyn (unattached), Deiniol Jones (Cardiff), A Jones (Neath-Swansea), M Davies (unattached), G Jenkins (Cardiff).
Replacements: H Bennett (Neath-Swansea), Duncan Jones (Neath-Swansea), D Morris (Leicester), J Thomas (Neath-Swansea), M Phillips (Llanelli), C Sweeney (Newport-Gwent), R Williams (Cardiff).