Australia resumed on 67-4 after lunch but Steve Smith and Beau Webster took that to 146-4, withstanding a hostile spell from Kagiso Rabada and Marco Jansen.

Having survived their bursts, however, Smith then edged part-timer Aiden Markram to slip in his first over for South Africa's only breakthrough of the session.

Just one from Keshav Maharaj's over and it's time for tea.

Only one wicket fell in that session, but it was the big one of Steve Smith.

It's been a closely-fought contest with Beau Webster playing a crucial hand with his 55 not out, while Alex Carey has counter-attacked with his 22 from 29 balls.

Image source, Getty Images

I'd better keep my colleague Stephan Shemilt happy by plugging his recent feature on Beau Webster, which you can read here.

We should have time for one more over before tea.

To those of you who enjoy seeing Steve Smith get out...

Alex Carey is putting the pressure back on South Africa just before tea. It's a role he plays so well.

Twice he guides the ball with exquisite timing between second slip and gully, much to Marco Jansen's frustration.

Andy Zaltzman
Test Match Special statistician

That is Beau Webster's second fifty in just his fourth Test match. In first-class cricket since April 2021, he has played 50 matches averaging 52.

Prior to that he averaged just 28 in his first-class career.

Vic Marks
Former England spinner on BBC Radio 5 Sports Extra

It's an important fifty in the context of this match because runs are hard to come by, but also for his career.

I'll just leave this one here...

50 for Beau Websterpublished at 47 overs

47 overs

Aus 174-5

Gets there in the end!

Beau Webster brings up his half-century from 69 balls with a single driven out to deep cover.

A crucial innings for Australia, and a determined one considering how shaky he looked at the beginning of the knock.

South Africa turn back to Marco Jansen, sensing the opportunity of a breakthrough in the 15 minutes before tea.

It's not a particularly threatening over, though, as Alex Carey pulls a short ball firmly past square leg for four.

Carey's making Beau Webster work for his half-century here.

Vic Marks
Former England spinner on BBC Radio 5 Sports Extra

That was a lovely drive, a silky, left-handed cover drive from Carey. He often gets Australia out of sticky situations.

Crunched.

Alex Carey drives Wiaan Mulder through the covers and holds the pose for good measure. A punchy start for the left-handed wicketkeeper-batter.

Beau Webster moves to 48 with a well-executed paddle off Aiden Markram.

South Africa's energy levels have gone up a notch since Smith's dismissal.

Off the glove.

Nothing to see here.

Has Aiden Markram got another?!

Alex Carey misses a sweep first ball and Temba Bavuma reviews with a second to spare.

Eventually, Wiaan Mulder's over comes to an end after two fours and three no-balls.

Alex Carey, another of Lord's favourite Australians, joins Beau Webster in the middle.