Heather Knight goes tumbling to her right at cover to cut off a big drive from Mignon du Preez, and then does an admin check on her knees and elbows. She's spent an awful lot of time jumping around today, and she gets a round of applause from Hartley to boot.

Charlotte Edwards
Ex-England captain on BBC Test Match Special

What I love about Mignon du Preez is that she's got so much energy at the crease. She sweeps and plays spin well.

Here's a couple of Du Preez boundaries for you to watch...

Enid Bakewell, one of the funniest people you could hope to sit and watch a cricket match with, is watching on from the stands. Good running, this, from South Africa, charging up and down the wicket to break a run of three Gunn dot balls.

Mel Jones
Former Australia batter on BBC Test Match Special

This is an interesting battle between Alex Hartley and Laura Wolvaardt as she missed with two pull shots, the third went through Hartley's hands - a catch which should have been taken - and the fourth has gone over the top.

Four! That's a cracking shot from Laura Wolvaardt, just taking a step to the side and pulling Alex Hartley over her head and down to the boundary. She's tried that shot a few times for Hartley but it's only just come off for her. Hartley winces before taking even a whiff of pace off the ball, which means Mignon du Preez has to throw her arms into a drive to get a single.

Mel Jones
Former Australia batter on BBC Test Match Special

Laura Wolvaardt will enjoy Jenny Gunn coming on, with a little extra pace to work with, compared to the spinners.

Image source, Getty Images

Here's Jenny Gunn, all arms and legs, and she fires down a delivery that Laura Wolvaardt spoons up to Fran Wilson. The ball bounces, Wilson takes aim - oh, and she just misses the stumps! Gunn, in front of the stumps, tried to help the ball on its way but she ended up groping at the Bristol air. Wolvaardt seems to prefer the seam to the spin, and she drives wristily for a couple of singles.

Mel Jones
Former Australia batter on BBC Test Match Special

For Mignon du Preez in this World Cup, her lowest score is 20, but her highest is only 43.

Image source, Getty Images

A boundary! Mignon du Preez doesn't fancy this prodding around business. She takes a step forward to Alex Hartley and makes a bit of a meal of the drive, actually, having to adjust her wrists at the last minute to thread the ball through the covers. Oh, and again! A bit more aerially that time and Nat Sciver, diving in installments to her left, couldn't cut it off. Plenty of power behind that second boundary, mind.

Mel Jones
Former Australia batter on BBC Test Match Special

There's a real belief in this South Africa group, they're all on the same page and want to improve on things. Some of the senior players have played in the Super League and the Women's Big Bash League, and they've also had more support from Cricket South Africa and their sponsor. There's 14 players on contracts now.

Drinks have been and gone and in their place is Laura Marsh, twirling the ball from one hand to the other, and she picks up exactly where she left off. She concedes just two runs, with South Africa looking a little stuck. Opener Wolvaardt has taken 64 balls for her 35, and she doesn't look comfy at all against the spin.

And with that, the drinks head out onto the field.

Wolvaardt dropped on 34published at 18 overs

18 overs

SA 63-2

Alex Hartley, arms akimbo, walks in and drops Laura Wolvaardt! Oh, she really should have caught that. It came back at her hard from Wolvaardt, trying to hit back down the field, but Hartley got both hands up to it and it just burst through fresh air.

This is one you will want to watch again and again. Superb glovework from Sarah Taylor stumps Trisha Chetty from a legside wide bowled by Natalie Sciver.

England's spin twins are in action and it's slowed the run rate right down. Mignon du Preez has a word with her team-mate - there's a bit of frustration creeping into Laura Wolvaardt's game as she starts going after Laura Marsh's deliveries with hard hands. Just a couple of runs on offer.

Mel Jones
Former Australia batter on BBC Test Match Special

An interesting over from Alex Hartley - Laura Wolvaardt's just 18 years old, it's a really important phase of the game for her.

Time for some Alex Hartley. Her first ball is slow, almost like it's in slo-mo, and Wolvaardt has to adjust at the last minute to hoof it to Heather Knight at mid-on. Hartley speeds it up a touch and gives the ball a bit of air, and that limits South Africa to just a single.

Image source, Getty Images

Laura Wolvaardt loves a drive. Mind you, if I looked as elegant as she does playing it, I'd throw it at every ball I faced, too. She works a single here and there off Marsh, back leg bent, elbow high, as Laura Marsh fires through her third over.

Here's one of teenage South Africa opener Laura Wolvaardt's three boundaries, and one from Trisha Chetty:

Shot! Too much width on offer from Nat Sciver, and Laura Wolvaardt creams it to the boundary. Sciver goes short and Wolvaardt chops, and chops hard, but Alex Hartley comes haring round at third man to keep it to just a single.