Van der Dussen reverses Dunith Wellalage for four from his opening delivery, before Quinton de Kock does a cute little reverse flick to move the ball down to the boundary behind the keeper.

The surly looking South African then works a third boundary of the over off his legs, and inevitably doesn't look especially happy about it.

Steven Finn
Former England bowler on BBC Test Match Special

It felt as though something was going to give. That was the first over of pressure Sri Lanka have put on South Africa in about 10 to 15 overs.

Kasun Rajitha continues for Sri Lanka at the other end, having been struck for three fours in his previous over. Rassie van der Dussen pulls him for four, the ball going wide of short leg.

The South African subs have raced on with drinks - the umpires aren't looking especially happy with that. Unofficial drinks? I won't stand for the unregulated distribution of refreshments.

Jonathan Agnew
BBC cricket correspondent on Test Match Special

Oh! He's put it down! Not an easy catch.

Van der Dussen dropped on 71published at 26 overs

26 overs

SA 159-1

Thanks Tim.

Sri Lanka greet my arrival with five successive dot balls off the bowling of Dunith Wellalage, Rassie van der Dussen prodding the Sri Lankan spinner away with little flicks of his bat, which he then twirls in his hands between balls.

The South African batter then goes for the reverse sweep from Wellage's final delivery, crouching low and leaning forward. Pathum Nissanka is at backward point and he dives to his right but can't hold onto the catch. He wasn't full stretch - that was a chance.

Can South Africa kick on to a big total here? Or will Sri Lanka haul it back?

My esteemed colleague Mike Peter will talk you through the next 25 overs.

Rassie van der Dussen has played equally fluently here.

He picks up two boundaries off Kasun Rajitha down the ground. First driving the Sri Lankan seamer's third ball low through mid-off, then chipping him over mid-on.

Later in the over Van der Dussen effortlessly helps a ball slipping down leg to the boundary with a graceful whip of his hands.

The halfway point of the innings. Asked to bat first, South Africa will be the happier of the two teams at the moment. They have a decent platform.

Matthew Henry
BBC Sport in Delhi

It's not an amazing crowd, obviously, but it has grown and those that are here are making plenty of noise with their drums.

Quinton de Kock has been easy on the eye today as he thrashes Dunith Wellalage's first ball of his third over through the covers for four.

Wellalage comes back well in the remainder of the over, though, with four dots.

Steven Finn
Former England bowler on BBC Test Match Special

Quinton de Kock had his heart in his mouth. He walked down the pitch as he'd just hit a good shot down the fairway off the tee. But it just hit the inside of the bat, he's got away with one there.

SA 139-1published at 23 overs

23 overs

Quinton de Kock, batting in a cap, looking to go through the gears against the Sri Lankan spinners.

The South Africa opener creates some space for himself and carves Dhananjaya de Silva to the covers for four.

A couple of balls later and the left-hander goes down the ground and while Charith Asalanka is able to get finger tips on it at long-on the ball goes over the boundary for a maximum.

Henry Moeran
BBC Test Match Special commentator

Just for a moment there was a chance. It was agonisingly out of reach - a foot or so short?

A let-off for Rassie van der Dussen, who spoons Dhananjaya de Silva to mid-wicket with a flick of his legs but the ball drops just short of the hands of a diving Sadeera Samarawickrama.

Henry Moeran
BBC Test Match Special commentator

You might not get much emotion from Quinton de Kock, but you do get quality strokeplay.

Fifty for De Kockpublished at 21.2 overs

21.2 overs

Quinton de Kock reverse sweeps Dunith Wellalage to bring up his half-century.

It's been a controlled innings from the South Africa opener. Getting some sort of total on the board then backing their bowlers appears to be South Africa's gameplan here, rather than going ballistic and the risk that entails.

Dhananjaya de Silva has found a bit of rhythm with his bowling, at last. A couple of singles off his over, and Quinton de Kock is one run away from his fifty.

Here's how South African team-mate Rassie van der Dussen brought up his half-century a little while ago.

Steven Finn
Former England bowler on BBC Test Match Special

Rassie van der Dussen is a big rangy man. He can be a little slow to get going, but once he does he's very difficult to stop. He latches onto anything short.

When you get a partnership like this it's very difficult for a captain, it always feels like there's a gap in the field to exploit.

Rassie van der Dussen is using the crease well to throw spinner Dunith Wellalage off his lengths.

He shapes to come forward to the left-arm tweaker, but then rocks back deep into his crease and heaves it for four through deep mid-wicket.

Here's a clip of Quinton de Kock on the drive to the Lasith Malinga-esque slingy Matheesha Pathirana from a little while ago.

Steven Finn
Former England bowler on BBC Test Match Special

South Africa are just starting to build a really good partnership now. They're getting the pace of the track, spotting the moments from the bowlers they can take advantage of.

Dasun Shanaka is nagging away on a disciplined line to Quinton de Kock, eyeing a half-century of his own. He now has a century stand with Rassie van der Dussen for the second wicket.

There are a smattering a fans inside the Arun Jaitley Stadium at the moment but a few more people are starting to trickle in.