Williams has been part of a Blues outfit which has been under pressure this season and again failed to convince in Friday's home European Cup pool defeat to French side Stade Francais.

Now the 24-year-old full-back or wing has to rid himself of any negative thoughts and concentrate on taming a Springboks team which surprised many by winning the Tri-Nations during the summer.

Williams realises that Wales will be heavy underdogs but said: This is a professional game and you will be representing your country so you have to put things that affect you to the back of your mind.

It has been a difficult season for us so far but when you pull on the red jersey of Wales you know you will be representing your country and it makes you feel 10 times better.

If selected I will have to think about this game rather than our season so far and that's what I will do.

Williams, who may find himself on the wing to accommodate new Welsh skipper Gareth Thomas at full-back this Saturday, is one of the experienced men in the national squad despite his young age.

He made his debut four years ago against Ireland having been drafted into the senior squad from the Under-21 team that season.

And he admits that it will be up to people like him to guide Wales' relatively young players through Saturday's Test.

He added: The players that have been involved in the squad for a few years now can hopefully help the younger players.

There is a good atmosphere in this squad now and there has been for a while. It's a huge game and you have to realise you are playing against South Africa and it's not something that you take lightly.

We will have only been together for a few days while South Africa have been in camp for two weeks so we know it will be a fight for us.

They have big men and we realise that. They will take us on up front and we will need to find something to break them down there but I'm sure we can.

I am just looking forward to this to be honest and it will be good to get back into the groove again.