Tammy Beaumont used to be a gymnast. She's probably the shortest member of the England team, but also one of the most powerful. Holding the bat quite low down on the handle, she twice pounces on to the front foot to drive Ismail through the covers for boundaries. If South Africa's strength is their pace bowling, England dealing with it well.

South Africa skippers quite like a floppy sunhat. AB de Villiers so far this summer, now Dane van Niekerk today. Kapp, the bowler, has jet-black hair. Full and straight, two singles from the over. Bristol is an absolute picture - sunshine, no a cloud in the baby blue sky.

There's swing, but when ball refuses to move in the air, both of these South African bowlers are drifting down the leg side. Ismail, another teaching a piece of chewing gum a lesson, has her hair tied into a pontytail. When she strays on to Beaumont's pads, the Kent player tucks to mid-wicket for four.

Marizanne Kapp, the number-one ranked ODI bowler in the world, ties back her dark hair and eases in towards the shortish figure of Tammy Beaumont. Gentle hint of away swing, with Beaumont throwing her hands through a wide one to get four behind point. Kapp chunters to herself. Not a woman to cross.

Charles Dagnall
BBC Test Match Special

That was a wafty drive from Lauren Winfield. She was in no position to be playing that shot.

Plenty of spectators are still filing in as Winfield, flame haired, chews her gum with ferocity. Bounce from Ismail, an edge flying over the slips for four, then a loose drive that has the South Africans convinced of an edge. Appeal turned down. Feisty first over.

Anthems done, players taking their places under the Bristol sunshine. Lauren Winfield and Tammy Beaumont to open for England, Shabnim Ismail with the ball. She will form a potent pace attack with Marizanne Kapp.

BBC Test Match Special

As ever, we are all over this one. Test Match Special can be heard on your wireless and we will have highlights as they happen right here.

If you want to get involved, you can tweet on #bbccricket, text 81111 or email tms@bbc.co.uk

Ebony Rainford-Brent
Ex-England batter on BBC Test Match Special

This is the game which could change the tournament. South Africa are an emerging nation whose strength is in their bowling - that's why they were pleased England chose to bat first at the toss. England have got Australia and New Zealand to come and if they lost today - which is possible - it spoils what everyone thinks will be the narrative of this tournament... that it'll be an Australia v England final at Lord's.

South Africa, remember, bowled West Indies out for 48 on Sunday. In third, they are one place above England in the table. The top four qualify for the semis.

After this, England play Australia and New Zealand, probably the two strongest sides in the competition. Realistically, they have to win one of these next three.

England: Lauren Winfield, Tammy Beaumont, Sarah Taylor (wk), Heather Knight, Natalie Sciver, Fran Wilson, Danielle Wyatt, Katherine Brunt, Anya Shrubsole, Danielle Hazell, Alex Hartley

South Africa: Laura Wolvaardt, Lizelle Lee, Trisha Chetty (wk), Mignon du Preez, Marizanne Kapp, Chloe Tryon, Dane van Niekerk, Suné Luus, Shabnim Ismail, Ayabonga Khaka, Moseline Daniels

Ebony Rainford-Brent
Ex-England batter on BBC Test Match Special

I've always been a fan of Dani Hazell. She offers a lot of control and keep things tidy. You can see why Laura Marsh was brought in against all the Sri Lankan left-handers but Hazell offers good variety and I think it's probably the right decision.

Knight gets the rub of the coin toss and decides to bat first, meaning England will get the first look at South Africa's talented pace attack. One change for England. Four wickets are not enough to keep Laura Marsh in the side. She's replaced by Alex Hartley.

Now, as The Riddler said: "The real game begins".

Heather Knight's side take on South Africa in Bristol.

Defeat here and they could be struggling to reach the semi-finals.

...and two wins...

England in the Women's World Cup. One loss...

Image source, PA