After starting the day at 6-187, South Africa would have had hopes of bowling Australia out in that session. Instead, the Aussies added 90 runs for the loss of two wickets and watched Matt Renshaw get his groove back.

The Proteas won't mind seeing the pitch flatten out a little bit though.

Renshaw is happy to block this out it seems.

Harmer fires in a quicker one and finds Renshaw's pad, but it's down leg.

Renshaw pushes the penultimate delivery to deep cover and takes the single. Lyon has one ball to survive.

And he does it.

We're closing in on a delayed lunch so I doubt Matt Renshaw is going to take many chances here.

He tries the reverse sweep but misses everything.

Renshaw knocks the fourth ball of the over down the ground and takes the single.

And Lyon sees off the final two deliveries of the over. We'll get one more before the break.

And he fires in a seed from around the wicket, angling in and seaming away past the outside edge. That's a tough ball for anyone to play, much less a number 10.

Jansen is pushing Lyon back with some good stuff behind a good length. Will he fire in the full one soon?

Not yet. Lyon makes it through another maiden.

Straight after reaching his 204-ball ton, Renshaw is beaten on the outside edge and it races between slips and gully. I thought he nicked it, but it's been credited as four leg byes. Must have been all thigh pad.

He makes it through the rest of over and he looks like the weight of the world is off his shoulders. But he knows he still has more work to do.

Another lovely clip through the leg side for four and the big Queenslander beams as the ball races away. He whips off his helmet and the sweat messing up his hair is evidence of the work he's put in over the past two days.

(Supplied: Fox)

That's his second Test century and first since January 2017.

Nathan Lyon is facing Marco Jansen now, and he pitches on the thigh of Lyon, who clips an easy single off the first ball of the over. That's really poor bowling.

Renshaw is walking about the place and is rapped on the pads, but it's too high, as is often the case with Jansen.

Renshaw now needs to find avenues to runs without forcing Lyon to take too much of the strike.

SHOT! Renshaw walks across and manufactures a gorgeous leg side whip to the boundary.

He moves to 95 off 202. Make that 96 off 203 as he gets even further across to work behind square for a single.

Renshaw ended the last over almost coming unstuck as he tried to manipulate the field and got himself in a tangle. Nortje will want to keep him pinned at one end to build the pressure on the set batter.

Stunning. Nortje stays on the line and length to beat the outside edge of Renshaw, who again plays with a straight bat and doesn't chase it. Great bowling.

Four. A huge slice of luck as Renshaw's thick outside edge races behind point to take him into the 90s in a Test match for the first time in almost a decade.

He's defensive as he sits on 91. He'll still want a single to end the over, but has to be careful forcing the issue.

And he doesn't. Lyon will have to take some strike.

A big swing at a wide one from Mulder and Renshaw can only chuckle from the other end. Lyon leaves the next one on a tighter line and gets an approving nod from Renshaw.

Beautiful out-swinger to beat the outside edge of Lyon as he drives hard outside off once again. And it's another no ball. Once again, the runs are nice but I'm sure Lyon doesn't want to face all these extra deliveries.

Two runs off a chunked inside edge. Earlier in the over, Lyon would've just settled for one, but with only two balls remaining, they come back for a second.

And he sees it out.

And he's on the money to start as Renshaw leaves one going across him.

Renshaw is walking across his stumps and defending under his eyes. This time he plays so late and with such soft hands that the ball goes behind him to the slips.

Excellent fielding at mid-off by Ryan Rickelton to keep Renshaw on strike off the penultimate delivery.

And that's a maiden as Renshaw is squared up on the last.

So he remains stuck on the dreaded 87 for a little longer.

The right-armer hasn't been good to Lyon so far, but now he has a chance to bowl six straight at the number 10.

Four! Bad bowling from Mulder as he sprays down leg again and Lyon just helps it on its way to get off the mark.

He's staying outside off now, and Lyon is staying disciplined.

Can Mulder get one to seam or swing back in?

Not yet.

Lyon and Renshaw turn down a leg bye as Mulder goes too far that side yet again to end the over.

Can some express pace change things up for South Africa?

FOUR! A glorious cover drive by Renshaw to take him to 83.

This is his outright second-highest Test score by the way, albeit currently 101 runs shy of his biggest.

Matt. Matthew. What was that? He ducks under a bouncer then, while down on one knee, tries to uppercut. A rare moment of indecision from the Queenslander.

Four more! There's a proper uppercut, just glanced up and over the slips for another boundary. Using the pace beautifully.

We've seen a lot of cloud cover this morning, but the brightness returns as Wiaan Mulder continues.

Four! A huge flourish from Matt Renshaw as he steps across his stumps and clips away to the square leg boundary.

And now a lovely little late cut to take two behind point. That one wasn't really there to be cut, but Renshaw seems to have completely changed tack in these last two balls.

Another clip to mid-on and Renshaw is taking quick singles late in the over. Nathan Lyon isn't the fastest man in the team these days, but he's quick enough to make his ground.

He has two balls to negotiate, and again Mulder is way down leg.

Finally a decent line, but Lyon shoulders arms. And it's another no ball. I think Lyon would happily forego the team's run if it meant he could just get off strike.

Alas, another poor delivery that's too wide to tempt Lyon.

After Renshaw negotiates a couple of regulation Jansen out-swingers, the big leftie comes around the wicket. Surely he's not going to short stuff yet. This ball is only four overs old.

Short. Ish. And Renshaw clips off his hip for a single.

He has one ball at Lyon and, like Mulder, is too far down leg. Presumably hunting the hero ball that sends stumps clattering.

And again the seam away beats Renshaw's outside edge.

"Yes! Nononononono," is the call from Renshaw as he steps across and drives  wide of mid-on. But not wide enough.

A gorgeous off drive from Renshaw, but straight to Anrich Nortje at mid-off. That would've felt great off the bat for Renners, but Mulder will like seeing him throwing the bat at them.

Renshaw is walking all around the crease and this time he's able to clip a single to deep fine leg.

Mulder wastes one of two balls at Lyon by spearing way down leg.

And another one. That's a disappointing end for the right-armer.

Jansen starts again outside off and seaming further away. Renshaw leaves.

Edged! And again it drops short of the slips. Played well late and with soft hands, but for such a tall man, it must be tough to see a legitimate outside edge go to the grass.

Jansen strays onto Renshaw's pads, but he isn't looking to score as he defends to the leg side.

Renshaw is squared up but that seam away from Jansen and again Tristan Stubbs does well to save a boundary at deep backward point.

More frustration for Jansen.

I think the days of Renshaw willingly giving up the strike are now over.

Mulder oversteps on the first ball after getting Starc. Couldn't have done that last delivery?

A fair bit of movement in the deck still, but Nathan Lyon leaves outside off.