The spectre of the doping shock that rocked the Springboks in Edinburgh last week was still hanging over the team as they awaited the results from the latest batch of drug tests, which were taken after the game against Scotland.

Officially, Bok team doctor Craig Roberts pronounced himself happy that no fewer than six players were tested following the defeat at Edinburgh.

But he must be nervous about the possibility of more positive findings for the illegal stimulant that saw Chiliboy Ralepelle and Bjorn Basson sent home, especially seeing that the team's internal audit has still not turned up a rogue supplement to explain the failed tests.

"We're very glad they came and tested the guys. They pulled six of our guys and two from the Scots," said Roberts. "It usually takes six to eight days to get a result, so we'll be waiting on those."

Knowing rugby officialdom's not-so-cosy relationship with the Boks, it wouldn't be a surprise to see the results made available sooner than the Sunday after the England game this time around, if the testing of no less than six players was anything to go by.

Roberts said in the meantime they had told the players not to take their supplements until they found whatever substance led to Ralepelle and Basson's positive results.

"It takes 10 days to two weeks, so we're still in the process of checking," he explained. "At the moment we've told our guys to stop taking everything from that Sunday. They're getting their proteins from their meals and we've added extra snacks during the days after gym so they can take a bit of extra protein that way.

"We've just stayed away from all the supplements and obviously any vitamins and minerals that aren't on the list of substances you can use."

The hidden issue there must be how the players - who seem to need a supplement just to pee into the drug testers' cups in the modern age - are handling not being able to take their myriad support substances.

On the injury side of things, Roberts said prop Beast Mtawarira was the only concern as he sat out yesterday's training session with a "very mild medial collateral ligament strain on his knee".

Scrum coach Os du Randt said he hoped Mtawarira would be good to go on Saturday: "He's played well since he stepped in for Gurthro [Steenkamp], and we've done a lot of work over the last four weeks.

"It would impact things if he didn't play, so we hope he pulls through."

Du Randt said his reason for needing a fit Mtawarira was his belief that England represents the toughest scrummaging test on tour.

"If you look at our tour last year, where we got annihilated by club sides in the scrum, England are the biggest Test for me as a scrum coach," he said. "We're looking forward to it because that will determine if the guys have learnt something from the year, and we'll also see where we stand."

• Simnikiwe Xabanisa is on tour with the Springboks courtesy of British Airways.