Ollie Hayward: I can explain Tony S (13:57). Jos has England's fastest 3 ODI hundreds and just played for the IPL champions.

Image source, Getty Images

Rabada concedes another free hit and it's another lowish full toss, but Hales misses it before raging at the sky in annoyance. These deliveries are still whizzing down at 90mph+, and Hales works the last delivery off his pads for another couple.

Take a look back at Alex Hales' wristy boundary off Wayne Parnell.

Michael Vaughan
Ex-England captain on BBC Test Match Special

You feel for Jason Roy. He'll be in the dressing room watching these strokes thinking he's missed out. It's an absolute belter.

A change in bowling, as Chris Morris comes on. Hales gives him two balls to settle in before driving the third with a flourish for four. That brings England's 50 up, and a minute later the 50 partnership is up, from just 40 balls.

Andy Beal: I think its a case of who deserves to be selected above Jonny Bairstow because he simply has to play.

Sonney Stelling: Moeen Ali is who you leave out for Bairstow. Ali is wasted so low in the order and Root can be the 6th bowler!

Roger Warren: I'd leave out Morgan, never rated him. Once described him as a 'converted baseball hitter', literally hit or miss.

Cracking work from Root, up on tippy toes again and steering Rabada through second slip for four. And another no ball from Rabada! That's a big overstep and De Villiers comes jogging over for a chat with his bowler. The free hit is a lovely bit of bowling though, a big, quick yorker that Root digs out before stumbling over his own feet.

Image source, Getty Images

Small Man Peaky: Roy continues to flatter to deceive. England won't change opening partnership this close to CT, but Billings deserves to play.

Martin Hardy: You'd be hard pressed to find many English cricket fans who think Jos Buttler should be playing ahead of @jbairstow21, external

Donald Broon: Huge Bairstow fan but seems clear to me: Can't drop anyone in the top 6, and need the insurance/variety of six bowlers.

Shot! Hales shuffles across his stumps and flicks his wrists on a straight delivery from Parnell for another boundary. Root then decides to take on De Villiers as he drops into the field and runs. De Villiers, quick as a whippet, charges across and takes aim and the ball just skips past the stumps. Root grins at him in response, before Hales ends the over with another boundary.

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

South Africa's bowling has been very tight - both have bowled with pace. England will want to settle in. It's a good wicket.

Lovely from Root, up on his toes and guiding a Rabada delivery away to the boundary. That's an overstep from Rabada, though, and a free hit for Hales. Ooh, and it's a rubbish, low full toss that Hales smacks away to the boundary. Eleven from the over for England.

Jason Roy faced just six balls this afternoon before he edged Wayne Parnell behind for 1.

Took me an embarrassingly long while to work out what 'YJB' meant. Who do you leave out to bring Bairstow in, though? Let me know your thoughts. Parnell continues and Root sneaks a couple from the first delivery, before Hales pats away the rest of the over.

Sam Rogers: Need a lot from Root/Hales to set the platform England can’t seem to play without. SA won’t give much away in the field either

Peter House: At least we have YJB to come in and steady the ship... Oh wait the selectors are morons

Rabada will continue, two slips lurking. He's regularly reaching 90mph and he gets Hales driving loosely. The ball beats the inside edge, de Kock can't get a mitt to it and it's away for four byes. The last ball over he over is a loose half volley and Hales knocks it off his toes and to the boundary.

Joe Root is the next man in, getting exactly the sort of reception you'd expect from a Yorkshire crowd, and he's off the mark with a nice cover drive. Alex Hales then ends the over with a swipe at another pitched up delivery, but he connects with fresh air.

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

Very little foot movement from Jason Roy, it was a little bit wide and he played a loose shot. He wouldn't have wanted to start the series this way but well done to Parnell.

Image source, Reuters

Kagiso Rabada is already touching a shade under 90mph as he steams in for the opening over.

The young paceman hits a fine line straight away and finds the edge of Alex Hales and Jason Roy, but the ball flies safely down to third man.

Steady start for the hosts.

Image source, Reuters

Both sets of teams observe a minute's silence to remember the victims of Monday's attack at Manchester Arena.

It's impeccably observed. Alex Hales and Jason Roy will open for England. Kagiso Rabada has the ball in his hand for South Africa.