Strettle is in hospital after being hit by the stomach virus that has affected a handful of England players, including Wilkinson.

While Wilkinson has returned to training after spending two days in bed earlier this week, Strettle’s tour could be over.

Gloucester back Iain Balshaw will replace him and win his 30th cap, with the bench vacancy caused by his promotion being filled after England train at Vodacom Park, Bloemfontein on Friday.

Wilkinson said: “I am okay. I had a couple of days in bed, and I am coming through the back end of it now. It should be perfect timing – I trained today.

“I have only really missed one training session, and I am fully fit and healthy.”

But Strettle, who shot to prominence during England’s RBS 6 Nations campaign earlier this season, has not been so lucky.

England team doctor Simon Kemp said: “David’s vomiting continued through yesterday, and he was unable to take fluids by mouth.

“He was therefore admitted to a local hospital for rehydration and monitoring, and while he has made good progress, he will not be fit to play on Saturday.”

England can now only hope Farrell makes it, and assistant coach Mike Ford added: “Andy is a tough guy. I think he will be there for us on the weekend.”

Wilkinson, whose career has been repeatedly stalled by injury setbacks since he kicked England to 2003 World Cup glory, starts his first Test for three months.

There are many who feel he should have been rested from the two-Test South Africa mission – which sees England facing the Springboks without numerous leading players – before far more significant business of World Cup training camps, warm-up games and then the Webb Ellis Trophy defence in France.

But he said: “I have an opportunity to represent my country on a tour to South Africa, so I don’t really need any other reason to be here. I am here to try and add whatever I can to the team and the squad.

“On a personal front, I am here to try to better myself, to further my learning which has been a bit stunted over the last three years, and get some experience under pressure against one of the best teams in the world.

“It is a valuable opportunity to learn and learn quickly, which is of the essence with the World Cup just around the corner. It is an ideal place to be, provided we go out there and we perform to our potential.”

Wilkinson steered England to a famous victory over the Springboks in Bloemfontein seven years ago, kicking all their points for a 27-22 success, yet he is not into history lessons and also distances himself from talk of South Africa wanting revenge for a 53-3 humiliation at Twickenham in 2002.

He added: “It is nice to go back to a place you have been before, but you quickly learn in this game that these are one-off moments.

“That occasion (Bloemfontein) took all 22 English players on the day and all their efforts to turn that game to what it was. It’s seven years on now, and two totally different sides.

“I have always been for the here and now in terms of rugby. I think 2002 was a bit of a one in a million game. It just so happened to turn our way, and I think it snowballed and maybe the scoreline didn’t quite tell the story.

“It was a big win for us, but there have been numerous games between the countries since then. In terms of avenging stuff, I don’t really see it that way.”

And as for England being written off, both this weekend and in Pretoria on Saturday week, Wilkinson said: “I don’t think I have ever gone into a game and thought about keeping the score down, to be fair.

“You go out there, you hit the first whistle and the first minute and react to whatever happens.

“I have been involved in games when we have been on the wrong end – Ireland, just recently, was one of those – but never once do you think about keeping the score down or you are going to lose before you start, because it would be pointless playing.”

For skipper Jason Robinson, who will bow out of rugby after England’s World Cup campaign ends, Saturday’s clash is also about opportunities, rather than damage-limitation.

Robinson said: “I have always wanted to play against the best players in the world. The challenge is there, and it is about us rising to it and meeting it head-on.

“We are underdogs with a lot of things going against us, but that is what sport at this level is all about – stepping up to those challenges.”