Ashes 2019: Australia's Steve Smith a total one-off, says Jonathan Agnew

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'Remarkable, eccentric, extraordinary batsman' - Smith reaches 200

Steve Smith is a total one-off.

The Australia batsman's double century made it a chastening day for England at Old Trafford.

The opportunities were there but England didn't take them and, while there is plenty of time left in the fourth Test, they may look back on this as the day the Ashes slipped from their grasp.

Smith is aesthetically exhausting to watch with all his mannerisms but he's mighty effective. A run machine.

England have been told not to engage him at all, no matter how much he might be winding them up with his strange leaves.

They should be more aggressive to him - though it may be too late. We may not see him bat again in this game, with England on 23-1, trailing by 474 after day two.

But perhaps England should get into him a bit, try to make him feel uncomfortable. They should engage him and try to drag him out of where he likes to be.

He shows extraordinary determination, commitment and concentration and seems so comfortable at the moment. England do need to look at that.

Smith just goes on and on. He's a curious player, a very eccentric player.

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He'll treat the same ball differently - late in his innings Stuart Broad bowled him a half volley and Smith simply patted it back to him. Two balls later, he hit the exact same ball wide of mid-on for four.

I enjoy watching him bat because he fascinates me - although as a bowler I would be really fed up of the way he leaves the ball and the way he looks at you.

He is just unique. India captain Virat Kohli is so pleasing on the eye and he hits the ball where you'd expect but Smith doesn't - he looks like he's playing French cricket sometimes.

He has incredible hand-eye coordination but he's also very capable of playing some lovely shots as well.

The year-long ban for his part in the ball-tampering scandal clearly hasn't affected him adversely at all, apart from perhaps his image and his reputation.

He has come back refreshed and totally focused, whereas David Warner hasn't settled back into Test cricket.

At the start of the series I wondered about Smith because he is quite a jittery and anxious person, but thought Warner would brazen it out. But it's the other way round and class will out.

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For England, the chances were there. Smith was, even by his standards, frenetic to start with - the best batsman in the world looked like he was playing his first Test innings.

He was like a cat on a hot tin roof and he gave that six out of 10 caught and bowled chance to Jofra Archer, which he didn't take.

Then Jack Leach bowled him a beautiful delivery and had him caught, but off a no-ball. It says everything about cricket - one minute Leach is the hero with his one not out at Headingley, the next people are saying, 'What on earth is the spinner doing bowling a no-ball?'

He was trying to hold it back a bit, which meant he extended his delivery stride, but he'll be tortured by that.

And then substitute fielder Sam Curran dropped Tim Paine after lunch - there were so many opportunities for England to keep Australia down to something manageable.

But this is not manageable now. England have to batten down the hatches. If they succumb, they will lose.

Let's see how much confidence they have taken from Headingley. Let's see if they have some application about them. Australia have clearly made a huge step towards retaining the Ashes.

The worry is that there is some big spin for a second day pitch and it could turn a long way towards the end of the game. You can expect Australia off-spinner Nathan Lyon to bowl a lot.

It is Australia's game to throw away now. There are still three days to go but, on England's recent batting record, they are going to have to play out of their skins to save this match.

It is unlikely they can win from here but somehow they have to make sure that Australia don't.

It's going to be a real challenge to see out these next three days and try to keep the series alive for the final Test at The Oval.

Jonathan Agnew was speaking to BBC Sport's Jack Skelton at Old Trafford.