Mitchell Johnson.

Mitchell Johnson. Photo: Getty Images

CAPE TOWN, South Africa South Africa coach Russell Domingo is wary of another Mitchell Johnson mauling in the Test series decider at Cape Town.

Australian paceman Johnson claimed career-best Test match figures of 12-127 in the first Test on a bouncy Centurion pitch, also striking brutal blows to the helmets, hands and forearms of the opposition.

But in Port Elizabeth, Ashes hero Johnson finally crashed back to earth as he was restricted to match figures of 3-121 and rarely had any of the Proteas in a spot of bother.

Domingo suggested his charges should take confidence from how they mastered Johnson at St George's Park, but that it would be foolish to expect the same in the third Test at Newlands starting on Saturday.

"He's a wonderful bowler, he has been in great form for the past couple of months. If we get complacent against Mitchell Johnson I think we do it at our own peril," Domingo said.

"I don't think we've nullified him at all.

"There'll always be something in the back of your mind, and knowing he's the guy who can turn a session around, can turn a match around. You've got to be on your guard every single time."

Domingo was more certain about the advantageous effect a last-start win would have on his team.

"A breakfast area the day after winning a cricket game and losing a cricket game are two totally different places," he said.

"After a good win there is so much more energy.

"There is a lot of tension after a loss. There is a lot of reflection. A lot of what-ifs. Could we have, should we have."

AAP