Cook lets the ball run off the face of the bat and hurtles down the wicket for a quick single, with Root pushing his bat over the line as the return throw comes in. Roach fires down another short ball, Root goes after it with a pull - and ends up toe-ending it, rather lamely, into the turf. Sir Curtly is right. He's not quite found his rhythm yet, and he has a suspicious prod at the pitch before flicking away a single that brings up the 50 partnership. It's come up from exactly 100 deliveries, which is very aesthetically pleasing.

Image source, PA

Sir Curtly Ambrose
Former West Indies fast bowler on TMS

Joe Root keeps looking at his bat, he can't quite get his timing right. I wouldn't be surprised if he changed it.

Another change for West Indies, with Alzarri Joseph returning. Root stays camped deep in his crease, forcing the ball away towards the fielders, before Joseph offers up a hint of width and Root slaps it towards cover. He has another glare at his bat before having a bit of swish at a wide delivery, connecting with fresh air, rather than the ball. Maiden.

Sir Curtly Ambrose
Former West Indies fast bowler on TMS

Cummins swung the pink ball a bit earlier but other than that there's been nothing much to write home about. It will probably change in the evening.

Kemar Roach is back, and he's greeted by a jab from Alastair Cook that goes fizzing away for four. That was short from Roach, not really getting up that high, and Cook stuck a leg in the air and swiveled to hustle it away. Roach grunts with effort as he bangs another wide delivery beyond Cook's off stump, and the opener lets it go swinging past him.

Here's a couple of boundaries from this pair for your delectation - they've put on 45 runs so far.

The opener debate would be a lot easier if one of you lot could invent a cricket cloning machine. You could have two Alastair Cooks at the top of the order, and that's the problem solved. These overs are following a pretty similar pattern at the minute - dot balls, broken by a few boundaries here and there. The first four from Root is a cover drive that goes flying across the field, before he flicks Holder's final ball off his legs with a flourish.

Chris, struggling to see the pink ball, in West London

Miguel Cummins has a half-shout against Cook as he chases a leg-side delivery, but that brushed the pad, rather than bat, and the umpire shakes his head. Cook then cuts, and cuts hard, playing away from his body, and picks up four runs for his troubles. The tall figure of Jason Holder is working hard on the pink ball, shining it against his trousers, before Cook lets the final two balls of the over go by.

Here's how Tom Westley fell earlier in the afternoon, given out after a fantastic review by West Indies.

That's four! Joe Root takes a step back and drives, the ball bursting through the waiting fielder's hands at point and running away to the boundary. A rare mis-step from Jason Holder there, offering up something short and wide, and Root took full advantage. The West Indies captain returns to targeting the off stump, and Root returns to letting the ball go through to the keeper.

Stephan Shemilt
BBC Sport at Edgbaston

Image source, BBC Sport

A different kind of beach cricket...

Cook gets slightly deceived by a slower ball from Miguel Cummins, taking a step forward and chipping the ball rather aerially up towards an advancing fielder. Cummins glares at Cook but the batsman adjusts himself, before ignoring a delivery that slides down the leg side. It's all gone very quiet out in the middle, although there's a nice buzz from the crowd.

Chris Harvey: I reckon by the time we have a decent opening partner for Cook, we'll need to find another one to replace Cook.

Four fellas dressed as bobsledders take their seats in the crowd as Root punches a drive off the back foot. It's a tidy over from Jason Holder, very little width on offer, with Root ignoring anything he doesn't need to play at. A maiden.

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Some leg-side rubbish is dispatched with ease by Alastair Cook, knocking the ball off his hips and getting enough of a touch to help it to the third man boundary. This is a bit off from Miguel Cummins, actually. He's been so accurate but he goes too full, allowing Cook to drive for a couple, before another leggy delivery is flicked away disdainfully.

We've just been having a debate about this pink ball - it seems, to me anyway, to have had a bit of extra zip this morning, but nothing extravagant. The real test will be under the lights, but it's also a touch difficult to pick up. Let us know your pink ball thoughts using #bbccricket or text 81111.

Tim Marshall: I think the England number two batting position is one of the most cursed positions in sport!

Jason Holder will carry on, drawing Root forward and the England captain gets a thick inside edge onto his pads. That's over-pitched from Holder though, full and wide and Root throws his arms into a drive that goes fizzing away for four. That's good work from Root, not hitting it too hard but with enough oomph to beat the two fielders at cover.

Imagine facing this fella under floodlights with a pink ball. Actually, don't. It might give you nightmares.

Sir Curtly Ambrose is the special guest on this week’s Stumped podcast, which you can download right now.

The Windies fast bowling legend gives his views on day-night Tests and the future of cricket in the Caribbean.

Plus, Alison Mitchell takes a trip to the Dukes factory to find out how the pink ball is made.

And the unlikely rise of cricket in Serbia, India-Sri Lanka reaction, and how Australia might copy England in this year’s Ashes.