The Ashes, second Test, day two RECAP: Nathan Lyon forced off with calf issue as England stages fightback; Steve Smith scores another century on English soil

What a fascinating Test match this one is developing into!

After a brief flutter to begin the final session, England steadied nicely and you've got to say it's their day today, considering how far ahead Australia were to start day two.

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The home side go into stumps 4-278, 138 runs behind Australia's first innings total.

All eyes from an Australian perspective will be on the health of Nathan Lyon after he limped off in the final session with a calf injury.

Tune in tomorrow for all the day three action!

England playing right into Australia's hands here and they've allowed the tourists to get right back on top.

The last half hour has seen Australia go almost exclusively to short pitched bowling and England's batters keep trying to take it on and keep perishing.

Joe Root is the latest man to fall after top edging one from Mitchell Starc that is brilliantly taken by Steve Smith.

England has now lost 3-34 since the tea break, all three wickets virtually thrown away.

Australia are PUMPED!

The pitch isn't doing much but they've gotten creative with their fields and bowling attack and it's yielded two quick wickets.

Ben Duckett looks to hoick a Josh Hazlewood bouncer to the boundary but hits it straight down David Warner's throat at deep fine leg and he's got to go for 98!

Suddenly the tourists are right back on top and there's now two new batters at the crease for England.

Cam Green has removed Joe Root but it's a no ball!

It's another short delivery and it catches the glove of Root and lobs through to Alex Carey, and the Aussies are over the moon.

However, Root is called back after replays show that Green had overstepped.

Will that one burn the Aussies?

"There's certain batters you don't give a chance to," Pietersen says. "This is a huge error."

"Ashes series can be defined by moments like that," Ricky Ponting adds.

Oh no! What's Ollie Pope done there?

This is the bad side of BazBall on full display here.

There's absolutely nothing happening and England is right on top and he's invited pressure by going for an ill-advised hook shot and hits it straight down Steve Smith's throat.

Much needed wicket for the Aussies.

Oh no, this is not good for Australia, Nathan Lyon has come up hobbling after chasing a ball in the outfield.

Australia's sole wicket-taker today looks to have pinged his right calf and can barely walk.

He's eventually helped off the ground by a trainer and looks absolutely despondent.

"He's struggling here. Whether he's cramped or tweaked a calf," says former England skipper Nasser Hussain on commentary.

"Remember, a 100 consecutive Test matches, the first bowler to do that. This doesn't look good.

"This could be a big moment in the Test match, in the series. He is a major, major man in this attack. He is pivotal in this attack."

"He is in pain. It doesn't look like cramp," fellow England great Andrew Strauss adds.

"With a cramp you're looking to stretch out that muscle. It looks like he's struggling big time. That is not a good sight if you're an Australian supporter.

"You can see he's walking almost on the side of his foot there, so that looks like a significant calf injury to me.

"That's really hard to watch. It really is an awful sight. You can tell from the look on his face, the enormity of it is really settling in for him there. Awful scenes."

"Having been the recipient of a couple of calf pops, and they are pops because the muscle just feels like it pops, it's a problem," Kevin Pietersen says.

"Just the way he was walking there, it definitely wasn't cramp. He was walking on the side of his foot and trying to protect that calf.

"That's the series over if it's a pop for Nathan Lyon."

Not much going Australia's way on day two so far and this incident sums up the tourists' day in a nutshell.

Pat Cummins puts in a dive to try and stop a Ben Duckett drive but the ball bounces awkwardly and collects him on the head instead and bounces past him.

Cummins is briefly forced off the field for a check-up but he soon returns.

Pat Cummins has thrown the ball to Cam Green to start the final session.

What can the youngster conjure up?

Another massive session coming up.

A solid session in the books for England, maybe their best of the series so far and we've well and truly got a match on our hands!

After the two openers survived a tricky period prior to lunch, they came out of the break full of intent and made the most of excellent batting conditions.

Zak Crawley will be livid that he gave his innings away after looking excellent en-route to 48.

Since his dismissal, Ollie Pope has come in and proven himself to be a great ally to Ben Duckett, who has continued to look better with every passing delivery.

Work to do for the tourists.

Ben Duckett has his first Ashes half-century!

The left-hander whips a Mitchell Starc delivery to the boundary to reach the milestone and England is building another handy partnership here.

Ollie Pope has raced to 32 off just 39 deliveries.