Johannesburg - Spinner Keshav Maharaj is expected to play a major role in South Africa's efforts to win the fourth and final Test against Australia at the Wanderers. 

The Bull Ring pitch is not known for assisting the spinners, but there was plenty of turn on offer on Saturday for both Maharaj and Nathan Lyon, in particular. 

South Africa have batted themselves into an almost unbeatable position. They lead by 401 runs with seven second-innings wickets remaining, and with two full days to play it is impossible to see the Aussies coming back to level the series. 

Maharaj (3/92) picked up two wickets on Saturday morning as the Proteas bowled Australia out for 221. That gave the hosts a lead of 67 and they could have put Australia back in if they enforced the follow-on. 

Skipper Faf du Plessis opted against that tactic, and Maharaj helped explain why.

"It’s been a really long season for the boys, so we did want to give our fast bowlers a bit of a rest," he said after the day's play.

"With the way conditions are right now, it’s a lot harder to bat in the second innings so hopefully with the pitch deteriorating it gives us a better chance of trying to win a Test match."

The decision not to follow-on was also likely made easier, Maharaj said, by the fact that Morne Morkel picked up a side strain in the opening session of the day. 

"I suppose you could boil it down to that as well because he is a big impact in our bowling unit. I think he’s going to be ready on from tomorrow onwards," said Maharaj. 

If Morkel's role in what is his final Test match is limited, then Maharaj will become an even bigger player for the Proteas. 

By the looks of the wicket, he is expecting to have a major say.

"Conditions would say yes, but I think collectively we’ve bowled well as a team in the series," the 28-year-old offered.

"There will be a lot of emphasis on the spin, but I actually think it’s turning and bouncing too much to actually find an edge. We’ll take it in our stride."