Well then. Mason Crane is going to bowl with the new ball.

Stephan Shemilt
BBC Sport in Sydney

Yesterday, I said it was hot. I was a fool. That was sub-zero compared to today. It's like walking around in an oven set to gas mark one and we're still an hour from midday.

It's doing nothing.

There might be the slightest hint of away movement from James Anderson, and the ball's nipping through to Jonny Bairtstow at a decent height, but there's nothing to trouble Shaun Marsh. He watches the ball like a hawk and plays out a tidy maiden.

Graeme Swann
Ex-England spinner on BBC Test Match Special

Australia are scoring fairly easily with this old ball so England may as well give Jimmy Anderson a new one to see if he can whip one out. Then you can give the spinners a harder ball to bowl with too.

New ball availablepublished at 23:44 Greenwich Mean Time 6 January 2018

23:44 GMT 6 January 2018

The third new ball is available for England - and, after an extra over with the old one, Joe Root has decided to take it.

It'll be James Anderson to replace Moeen Ali.

Good reactions from Mark Stoneman at short leg allow him to throw down the stumps as Shaun Marsh comes out of his crease, but the batsman thrusts his bat back with plenty of time to spare.

Crane looks a little stiffer to me this morning - the ball's not quite coming out right just yet. Mitch Marsh plays around a fuller ball but he gets enough of something on it to run it past James Anderson at leg slip, and away for a single. Crane's lucky that a wide delivery doesn't quite get the treatment at the end of the over.

Whenever England tour, it always feels as though there's a player who is never going to get out. Virat Kohli in India springs to mind from back in 2016 - it felt as though I spent every night of that series watching Kohli bat.

A better over from Moeen to Shaun Marsh, although a short, wide delivery is belted away for a couple through third man. Moeen goes fuller, forcing first Shaun and then Mitch to defend.

Conventional wisdom seems to be that Australia will go for a bit of bish-bash-bosh this morning, then declare at lunch.

Mike Hussey thinks they'll go on longer to deliberately rub England's nose in it and, to be honest, I'm inclined to agree with him.

Ooh, that's four. Mason Crane tosses the ball up invitingly and this time it is Marsh Bro Jr, Mitchell, who frees his arms and bunts the ball to the boundary. He nailed that.

He doesn't quite connect with a second full toss, spearing the ball towards a fielder, and Crane readjusts his length to keep Marsh on the defensive.

Double spin for England - here's Mason Crane.

Graeme Swann
Ex-England spinner on BBC Test Match Special

Mitch Marsh came down the wicket and gave him a big hug - I love to see that.

It was a very relieved celebration from Shaun - he had obviously been sweating on it last night. Well done, well played.

Image source, Getty Images

And Shaun Marsh celebrates his century by cracking another boundary from the final ball of Moeen's over.

Simon Mann
BBC Test Match Special commentator

What a pick he has been for the Australia selectors.

Image source, Getty Images

100 for S Marshpublished at 157.5 overs

157.5 overs

There it is! A second Ashes hundred for Shaun Marsh!

It's full from Moeen, and Marsh carves im through the covers for a sumptuous boundary. He knows from the moment the ball leaves the bat that it's going for four as he takes off his helmet and raises his bat to the crowd.

He gets a giant bear hug from his brother Mitch, who looks even more pleased than Shaun at this ton. Lovely stuff.

And Shaun Marsh, two runs away from his second Ashes hundred, cracks a cut shot furiously towards the fielder at backward point.

Right then. The Marsh brothers are out in the middle, surrounded by a flock of England players.

It'll be Moeen Ali to open things on a scorching hot Sydney morning.

Andrew Samson
BBC Test Match Special statistician

Of the 36 players to be 98 or 99 not out overnight in Test history, no-one has yet failed to complete a century.