Oh, that's superb, four more for Beaumont, who's virtually hitting fours in her sleep here. A leg bye brings Knight back on strike and means it's 11 off the over.

Knight has 50 from 64 balls, Beaumont has 89 from 110 - and surely only a spectacular collapse would prevent England winning from here.

50 for Heather Knightpublished at 36.3 overs

36.3 overs

Eng 173-2

Knight reaches her 15th ODI fifty from 63 deliveries with a single - her strike rate is even slightly superior to Beaumont's - but the home crowd are loving this as Beaumont powerfully blasts a four past extra cover. It was so powerful, neither Beaumont nor Van Niekerk - who was the nearest fielder - moved an inch.

Charlotte Edwards
Ex-England captain on BBC 5 live sports extra

Tammy Beaumont is executing her shots to perfection here.

With the field up, Beaumont swats Kapp for four over the ring of legside fielders. Knight moves to 49 as Kapp tries a slower, wide delivery and Knight can only just get a bat on it. Beaumont is seemingly able to take a single off every delivery. She has 80 from 106 balls. England need 62 from 84 balls.

Beaumont tries to cut an Ismail delivery but can't connect - and Lizelle Lee can't take it cleanly so a bye results. Ismail keeps it tight, just a couple more singles added - and it's powerplay o'clock.

And here's another big shot from TB

Charlotte Edwards
Ex-England captain on BBC 5 live sports extra

I'm expecting England to get these runs in the next 12 overs or so.

And if you're an England fan, enjoy these boundaries from Amy Jones, Tammy Beaumont and Heather Knight.

While the players take drinks, a quick catch-up for the innings - these were the two wickets which have fallen:

South Africa may be monitoring Charlotte Edwards' TMS commentary - as it is a return to the attack for Marizanne Kapp. Only a short run-up, but she generates plenty of pace from it. Some ones and twos mean the skipper is within sight of her half-century.

Time for drinks - with Alex Hartley sprinting on to deliver for England.

Here's one for the Heather Knight showreel.

Charlotte Edwards
Ex-England captain on BBC 5 live sports extra

Where's Marizanne Kapp? The best bowler in the team, and she's not come back for a second spell with the game in the balance.

100 partnershippublished at 33 overs

33 overs

Eng 153-2

Van Niekerk shuffles her pace options as Ismail returns for a third spell. A Knight single brings up the century stand - the England pair don't even realise that at first, and belatedly join each other in the middle of the pitch for a quick hug. Three from the over - England need 76 from 102 balls.

Charlotte Edwards
Ex-England captain on BBC 5 live sports extra

Lizelle Lee has actually kept OK today. We've not really noticed her as much. But it's a horrible job.

That four over the top was such a good shot from Tammy Beaumont. It was so straight, it didn't even matter if they'd had a long-on and long-off. I wish I could play a shot like that.

Van Niekerk takes herself off after five largely unproductive overs - and Ayabonga Khaka returns. The field comes in a little, but a full delivery on leg stump is brutally flicked over square leg for a first-bounce four by Beaumont. The Kent opener then launches another big blast over Khaka's head - again, a first-bounce four - and that's 150 up for England.

Ismail's off after an over and fellow seamer Klaas returns at the Nackington Road End. Lizelle Lee is up to the stumps and can do nothing as Klaas fires in a legside wide and England take the opportunity to run a couple. The scoreboard keeps ticking over - if England bat sensibly, they should see it home from here.

A young fan literally wrapped in a South African flag hides his head. Maybe he's tired and has had a long day. Or maybe he can't understand why Van Niekerk is bowling round the wicket either.

Charlotte Edwards
Ex-England captain on BBC 5 live sports extra

I can't understand why Van Niekerk continues to bowl round the wicket - and feed England's strengths!

In fact, I'm confused why she's even bowling. The seamers put the pressure on, which was released when Van Niekerk and Luus have come on to bowl spin - Knight and Beaumont are just milking them.

Having waited all that time for her first four, Knight sweeps Van Niekerk for her second with expert placement between two fielders. Seven from the over, and Van Niekerk has a scowl on her face.

South Africa turn back to the pace of Shabnim Ismail - but England keep rotating the strike well, with captain Heather Knight particularly adept at just clipping the ball into the leg side and scampering singles. Knight gives England a boost with a four through mid-wicket as Ismail pulls the last ball a little too short and England profit from a misfield.

While Beaumont's 59 has come from 86 balls, Knight has almost imperceptibly made her way to a very useful 34 from 40. That was her first boundary.

Henry Moeran
BBC Test Match Special commentator

I just went for a walk to get some dinner and it felt like a really warm atmosphere.