None of those late runs were made under the pressure of a chase, however.

The wicket of Simon Harmer in the final session, bowled shouldering arms by a ball from Nathan Lyon which turned back sharply showed the difficulty ahead.

Harmer dismissed Travis Head, Marnus Labuschagne, Josh Inglis and Alex Carey in Australia's first innings - all recognised batters.

The 37-year-old Essex legend, who once considered playing for England, will be crucial.

As ever in such scenarios, the pitch will play its part.

The PitchViz rating - CricViz's way of assessing the difficulty of a surface - jumped to 6.6 in the final session, comfortably the highest (thus most difficult) rating of the Test.

After settling down in the morning, the ball, as would be expected as a Test progresses, was turning significantly more in the final session than at any point across the previous four days.

Interestingly, however, South Africa's false shot percentage was just 11% across day four, a drop from 18% on day three.

Uneven bounce has not yet been a factor but one ball to Rickelton shortly after tea also shot low.