Highlights on BBC Two at 00:20 BST (UK only)
Williamson starred with 100 for New Zealand
Hazlewood took 6-52 for Australia
Group A: Eng 2pts, Aus 1pt, NZ 1pt, Ban 0pts
Turning our attention back to England for a moment, there's been some bad news for Chris Woakes.
He's been ruled out of the Champions Trophy with a side strain after a scan yesterday evening.
He could only manage two overs against Bangladesh in England's Champions Trophy opener on Thursday and he'll now be sidelined for, potentially, up to six weeks.
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Theo Bowyer: Aggers and Boycott... more entertaining than an old married couple.
Matt Warmington: Mustard and Onions for Durham. The fantastic scorebook entry c Mustard b Onions always amused me.
Stephen Leatherdale: Richie Benaud and a microphone!
NZ 67-1
The brollies are up in the crowd - it seems like it's only a light shower, but it's pretty dark over Edgbaston. Kane Williamson, up in the dressing room, is gawping at a laptop screen.
A brilliant shot, but keep an eye out for the catch in the crowd. Good hands from that man, the sort of catch that may just slip through your fingers a little later in the day.
James Taylor
Ex-England batsman on BBC Test Match Special
I've enjoyed the way New Zealand have gone about it. Guptill was very elegant, probably the most elegant in the game, then Ronchi and Williamson have kept up their intent and played beautifully. Australia gave them width and it's not what you expect from them.
The Australia players are trooping back into the dressing room as the first spots of rain appear on the camera lens. It's been a profitable morning for New Zealand - Australia haven't got their lines right and it's let the Black Caps get off to a decent start.
NZ 67-1 (Williamson 24, Ronch 16)
Right. Deep breaths, everyone. The ground staff are lurking by the covers as John Hastings takes the ball. The umpires converge and we're going off!
A leisurely chip over midwicket makes it way soundly to the boundary.
James Taylor
Ex-England batsman on BBC Test Match Special
That is shambolic. Ronchi, as amazing hands as he has had so far, his urgency between the stumps is shambolic at best. Very poor. It's brilliant that he sacrificed himself there but the lack of urgency frustrates me.
We somehow don't have a run out, but dearie me, that was dreadful from both teams.
Williamson knocked the ball away for a single but both men were in the middle of the pitch as the fielder at mid-on picked up the ball. Ronchi had completely given up but the throw was terrible, and Wade, who had a real job collecting the ball, dived and missed the stumps! What a shambles.
NZ 65-1
What on earth are you doing, Ronchi?! An absolutely horrible bit of cricket from everyone involved. Do we have a run out?
James Taylor
Ex-England batsman on BBC Test Match Special
For somebody who is so consistent on his line and length, Hazlewood's been all over the place. To a batsman of Williamson's class, you can't do that and he puts them away beautifully.
Six! 90mph from Cummins, and Ronchi just drives him, almost nonchalantly over mid-off for six. Brilliant, absolutely brilliant. Just a casual looking drive but there was so much power behind it.
Shot! A decent over from Hazlewood, trying to tempt Williamson outside off stump, is rounded off with a short ball that Williamson pounds away for four. That was lovely; perfectly controlled, Williamson spinning and thrashing the ball to the boundary.
Martin Guptill with a great start, but a leading edge flies straight to Maxwell. Hazlewood with the breakthrough.
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Liam: Surely it has to be Shane Watson and LBW going together?
Jo Lee: Walsh and Ambrose ... terrifying.
Paul Derry: Graeme Swann and DRS, a perfect combination.
Danyaal Hamdani: The 2 W's. Wasim and Waqar.
Williamson 8, Ronchi 17
Here's Pat Cummins, and there goes Pat Cummins! Not a controlled drive from Williamson by any means, the ball flying dangerously through point, but it's past Maxwell and away to the boundary. That's better from Ronchi though, wrists turning to flick the ball off his pads and away for four. Decent start, this...
Good arm, David! But Luke Ronchi is safely home.
Martin Guptill was in fine form before that dismissal, taking advantage of some loose deliveries from the Australian openers.
Kane Williamson is the new man at the crease. He's got the best cover drive going, for my money. As it happens, he'll settle for a scampered single to get off the mark.