England win by 109 runs
SA 262 all out: Tryon (70), Kapp (62), Wolvaardt (56); Davidson-Richards 3-35, Dean 3-42, Lamb 3-42
Eng 371-7: Beaumont 119 (107), Lamb 65 (66), Knight 63 (49); Khaka 2-64
England lead multi-format series 8-2 before three T20s
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Heather Knight slaps another one through the covers for four but in the context, that's not too bad a spell from Nonkululeko Mlaba.
She's bowled her 10 overs, taken one wicket for 68 and I'm sure she will be very glad not to have to bowl in the final 10 or so here.
Georgia Elwiss
England all-rounder on BBC Test Match Special
One thing is for sure, Sophia Dunkley is going to make Heather run a lot of twos so she needs to get those hamstrings loose!
Heather Knight loves a reverse sweep and she finally times one nicely off Chloe Tryon that races away to the boundary, thanks to a poor piece of fielding at point that lets it through.
Sloppy.
Understandably, the scoring has slowed a little since Tammy Beaumont got out for a magnificent 119.
Is that the bit of luck Heather Knight needed to kickstart her innings?
South Africa will certainly be hoping not.
Heather Knight is safely home!
As you were.
Emily Windsor
Southern Vipers batter on BBC Test Match Special
Heather Knight could be in trouble here.
Mlaba has definitely got a hand to it ... but did Knight make her ground in time?
Ooooh. Has Heather Knight been run out at the non-striker's end?!
Emily Windsor
Southern Vipers batter on BBC Test Match Special
There has been a couple of chances for South Africa and that is another one that has gone down.
Georgia Elwiss
England all-rounder on BBC Test Match Special
Mlaba is clutching her hand, that has hit her hard. She was always pulling her hand away from it.
Eng 241-2
Perhaps harsh to call it a drop but technically, it is.
Dunkley absolutely nails one back at the bowler, it's just to her left in her follow through. Mlaba sticks out a hand in hope but it clatters off her fingers and she's in some pain.
Sophia Dunkley takes the opportunity to have a drink and munch on a protein bar.
Anya Shrubsole
Former England bowler on BBC Test Match Special
I really would have liked to see Danni Wyatt to come in when Tammy Beaumont got out. It was a free hit, if she got out then so be it.
A twitchy start for Heather Knight, who plays and misses at one outside her off stump before completely mistiming a reverse sweep.
Heather Knight replaces Beaumont, in a place higher than the previous games because Nat Sciver is resting.
Can South Africa peg them back here? The game almost feels lost already but they have a chance to finish with some pride intact if they can take some quick wickets.
Anya Shrubsole
Former England bowler on BBC Test Match Special
It was a brilliant innings from Tammy Beaumont. She has really set up England for what should be a really big assault on the final 16 overs.
Image source, BBC Sport
Jonathan Agnew
BBC cricket correspondent on Test Match Special
It was a nicely-flighted ball, with a little bit of width.
It is the end of a really good innings. She is a classy player.
Beaumont st Chetty b Mlaba 119 (Eng 236-2)
A much-needed breakthrough for South Africa, and a magnificent innings comes to an end.
Mlaba deserved that wicket - she's been the best of the bowlers despite dropping a catch off her own bowling earlier. She also had another catch put down off her in the same over.
She bowls a lovely loopy delivery that Beaumont tries to smash out of Leicester, but is deceived and Trisha Chetty completes a simple stumping.
Alex Hartley
Former England bowler on BBC Test Match Special
After the wicket of Emma Lamb there was a real opportunity for South Africa to get themselves back in the game but they've just completely fluffed it.
A much neater over from Chloe Tryon concedes just four.
What can South Africa do? They've bowled two overs this innings but have also bowled more than two overs extra due to wides.