Indeed. This is surely a matter of when, not if, Australia declare and how big their lead will be.

England could well be looking at a nervy rearguard action in their second innings to escape Sydney with a draw.

Glenn McGrath
Ex-Australia pace bowler on BBC Test Match Special

I think Australia will bat until lunch tomorrow, if they can. When Mitchell Marsh gets in, he is naturally aggressive. He's going to score quickly.

Charlie, Lancashire

Graeme Swann
Ex-England spinner on BBC Test Match Special

This Test match is very much in Australia's favour.

So Shaun Marsh walks off unbeaten on 98, with younger brother Mitchell 63 not out.

The odd home fan might have been slightly narked at not seeing another century completed, but that's been an utterly dominant day for Australia.

Just two wickets fell all day. The first was the lesser-spotted Steve Smith dismissal, caught and bowled by Moeen Ali for 83.

The other was Mason Crane's maiden Test wicket - spinning it through Usman Khawaja to be stumped by Jonny Bairstow.

But that wasn't before Khawaja hit a majestic 171 to put his side firmly in control of this Test.

Graeme Swann
Ex-England spinner on BBC Test Match Special

England have toiled away manfully today. It's been a hard day. The wicket is still a splendid wicket to bat on when facing seam. The English spinners haven't been able to land the ball in the right area often enough. I fear Nathan Lyon might.

Mitch Marsh shoulders arms to a wide one, resulting in a smattering of light-hearted boos that he didn't try to return his brother to the strike.

A cut shot is mistimed and there is no run there either.

Just two balls remaining. The first is defended back to Anderson. More boos for Mitch. There will be no Shaun Marsh century today.

Here's the final ball of the day - and Mitch leaves well alone.

Here we go then...and Shaun Marsh can only flick James Anderson to leg for a single to move to 98.

James, Nottingham

Andrew Samson
BBC Test Match Special statistician

This is the Marsh brothers first hundred partnership in Test cricket. It's come up from 151 ball with 12 fours and two sixes.

Shaun Marsh shapes to clatter Tom Curran through the covers for his century, but picks out the man at cover.

Short ball next up, Marsh pulls it away but finds the man at deep square leg and can only jog a single.

A tired, short and wide ball from Curran and Mitch Marsh batters it past point to the fence. That's the 100 partnership for the brothers.

A dot ball to finish, which will put Shaun on strike on 97 for the last over of the day.

Tom Curran continues and Shaun Marsh flicks it away for a couple to move to 96.

He's one boundary away from a second century of the series...

James Anderson back on and his accuracy may prevent Shaun Marsh getting to a century before the close. On 93, he has to wait until the fourth ball of the over for one he can work away for a dashed single.

Mitch Marsh, fresh from that farcical episode last over, is back on strike. He drives off the back foot for no run.

Will he ensure Shaun is on strike for the next over? Yes, he just taps it into off.

Stu Harman: The standard of umpiring in this series has been as uninspiring as England's bowling on flat pitches.

Hot Spot from the other angle suggests Mitch Marsh hit his pad on the way through and that was the cause of the peak on snicko.

If so, that's a dire decision by the third umpire, who has given it not out for the wrong reason.

The right reason it wasn't out is that it was going miles down leg, which doesn't reflect well on the decision to give it out on the field.

Anyway, Mitch Marsh batters a four. Salt. Wound. Etc.

Dan Norcross
BBC Test Match Special

Whether there was an inside edge or not, I don't know. There was the faintest of faint marks on the bat. Joe Root looks like he's wondering if he can refer the referral.

Image source, Getty Images

The third umpire did not even get to ball tracking. He's judged that Mitch Marsh got a thin edge on that using snicko. Although it wasn't clear if the frames matched up and the ball wasn't in front of the bat when that peak occurred.

It was missing leg by miles anyway. Pretty poor decision by umpire Joel Wilson really.