Cummins continues to show more composure and technique than many in Australia's top order as he thwacks Woakes away through the covers for another boundary.

England desperately need something from somewhere. Anderson will stay on at the other end.

Momentum has swung like a James Anderson hooper at Trent Bridge in this Test and it's back Australia's way now.

Joe Root's delayed move to put his premier bowlers back on after lunch has been punished by this pair and Steve Smith especially looks imperious.

Root has seen enough - Broad is removed from the attack and Woakes is back on...

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

Image source, Getty Images

This must rank near the top innings for Smith. He's had to work for this. He has high expectations for himself. To get a hundred and relax? You won't see Steve Smith relaxing now.

Cummins on the drive now, clattering Anderson away to the fence and moving to an unbeaten 35.

That's his highest Test score, beating his previous best mark of 32 not out.

Another single to the impressive number nine to finish.

Andrew Samson
BBC Test Match Special statistician

This is Smith's sixth century in an Ashes Test, and his third at the Gabba. It is also his 13th as Test captain - the most of anyone in their first 27 Tests as captain.

Image source, AFP

Steve Smith scrambles another couple to the total.

His hundred took his 261 balls, with nine fours - his previous slowest century coming off 227 balls against India in Ranchi earlier this year.

A tremendous effort and a worrying knock for England, both in the context of this match and the series. They look bereft of ideas to get him out.

Simon Mann
BBC Test Match Special commentator

It's been a brilliant effort. He's showed his class, he's showed his temperament, and he's leading his Australia side up to England's total. You'll never get him out, not if he plays like this!

Image source, .

Century for Smithpublished at 107.4 overs

107.4 overs

No sign of any more false shots from Smith as Broad hangs it outside off, rolling his fingers across the odd delivery, but the Aussie skipper just leaves it well alone.

Broad goes round the wicket - and there it is, Smith belts a wide one through the covers and to the fence!

His 21st Test century and sixth in the Ashes. Majestic, nuggety, mercurial.

His slowest Test century but surely one of his best in the circumstances. Fantastic.

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When we said get some colour from around the ground Stephan...

Back on the field, Anderson continues to run in against Smith, trying to work him over but the Aussies captain just rocks in behind and defends. A maiden.

Stephan Shemilt
BBC Sport at the Gabba

I genuinely don't know what to say about this. So many questions....

Smith nabs a single off the first ball of the over - a feature of this partnership, showing how much faith he has in Cummins.

Again Cummins isn't fazed facing Broad, ducking, leaving and defending well.

We're around halfway in this Test match and it's still in the balance. Cracking stuff.

Australia probably the happier side right now though - it's been 105 minutes since the last wicket and this pair are coping well with the attritional cricket.

Andrew Samson
BBC Test Match Special statistician

Steve Smith has been batting for nearly six and three quarter hours.

Dan Norcross: It feels like he's been batting since before I got on the plane to Australia!

Image source, EPA

Cummins strokes one through the covers for two - pleasant shot and it's all looking too easy for the number nine out there.

This pair close in on a half-century stand as Smith closes in on what would be his sixth Ashes century.

This sums up England since lunch - it's all getting away from them.

Can Broad and Anderson inspire their side to take these final three wickets?

Image source, Reuters

Oh my word! Steve Smith plays his first truly rash shot of the day as Stuart Broad bangs it in at pace, with a bit of lift and the Aussie captain chucks his bat at it, doing very well not to edge it through to Jonny Bairstow.

Broad can't believe it. Smith is livid with himself - as you would be if you chucked away an Ashes century, six runs short after 249 balls.

He composes himself to pick up another couple, clipping it away in front of square.

Image source, Getty Images

Jonathan Agnew
BBC cricket correspondent on Test Match Special

That is not a delivery bowled by someone with a side strain. He's given that everything.

Well Anderson seems to indeed be fine, no sign of any strain in his delivery.

And that's promising - Anderson gives it everything, the ball rising and wobbling a touch as Cummins flashes at it, nearly nicking off.

The number nine puts that flamboyance away to defend the rest of the over.

"Maidens are like shelling peas for Anderson," says a colleague on the cricket desk.

Here's Jimmy...

Anderson back on - how will he fare?