England close on 112-2, needing 55 more to win
Duckett unbeaten on 50
Pakistan dismissed for 217, setting England 167 to claim historic 3-0 series sweep
Ahmed, 18, becomes youngest men's Test debutant to take five-wicket haul
Ahmed removes Babar, Rizwan, Shakeel, Wasim & Salman
There's a change of bowling as Mark Wood returns.
He didn't have much luck in his first spell and there isn't much assistance on the surface as Pakistan pick off three singles.
This partnership is worth 42 runs so far, which is a decent recovery after losing those three wickets for one run earlier this morning.
Stephan Shemilt
BBC Sport chief cricket writer in Karachi
That 3m umpire's call business is a daft rule, the modern-day equivalent of a batter not being given out on the front foot. It's either hitting or it isn't. The trajectory of the ball isn't changed by Babar using his feet. If he had been hit on the crease, that's out.
It was going to hit the stumps - but the impact was umpire's call over three metres.
Babar survives but England keep the review.
Have England got Babar Azam? There is a huge appeal from Ben Foakes and Jack Leach.
Babar had got himself well down the track, though.
Umpire Joel Wilson says no but England, after a brief discussion, send it upstairs.
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Saud Shakeel is fine to continue and is able to fend off the final ball of Ollie Robinson's over.
We have just under 20 minutes until lunch. How England would love to snare another one before the break to put them right on top. You sense this partnership is key to the whole innings.
Ouch. Ollie Robinson catches Saud Shakeel by surprise by banging one in short. Shakeel ducks but not enough and the ball smashes flush on his helmet.
It looks like Shakeel will be OK but the physio will come out to check on him.
Pakistan lead by 40
'Catch it' is the cry as Saud Shakeel skies one into the on-side, but it falls well short of Ollie Robinson running around from long-on and Pakistan run two.
Another unconvincing shot though. These two batters are scrambling around for fluency at the moment.
Babar 9, Shakeel 19
Ooh, a false shot from Babar Azam.
It is that threatening line outside off stump from Ollie Robinson that just straightens off the pitch slightly and lures Babar into a wafty drive.
Babar looking a little fidgety at the moment.
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Our school wicket was artificial turf with a small metal rim right around it. I was on strike, facing the worst player in the school. The delivery looked to be going very wide (more towards the square-leg umpire than me). However it smacked into the metal rim, turned 90 degrees, flew behind my legs and just nicked the off stump bail. One of the teachers - watching from the boundary, too far to see what had happened properly - convinced himself that the five minute coaching session he had given the bowler had turned him into the next Shane Warne.
Angus, Halesowen
Pakistan lead by 36
Saud Shakeel skips down the track again and lofts Jack Leach back over his head for a one-bounce four.
That will make Pakistan feel better. This has been a tricky half hour for the hosts.
A lovely wristy shot from Babar Azam finds a gap in the on-side. Mark Wood gamely chases it down and Pakistan run three.
There's still not much out there for the seamers at the moment. Their job is likely to hold up one end while the spinners do their stuff at the other.
A slightly awkward shot from Saud Shakeel disappears down towards fine leg, but is clawed back before going over the rope and Pakistan only run two.
Shakeel then shows some nifty footwork to try and work the ball into the on-side but Ben Duckett cuts it off.
England are strangling the scoring at the moment, cranking up the pressure with each delivery.
Pakistan lead by 26
Ollie Robinson is persisting with a tight, probing line outside off stump.
There may be a hint of seam movement, but not enough to trouble Babar Azam and Saud Shakeel.
Simon Mann
BBC Test Match Special commentator
England haven't won a Test match without Broad or Anderson in their team since 2007.
Leach 3-27
That's a lovely shot from Saud Shakeel, who plays a controlled sweep through deep backward square leg for four.
England bring in a boundary rider in response, with Shakeel nudging the ball in his direction for a single to end the over.
Alex Hartley
Former England bowler on BBC Test Match Special
Leach has bowled well. We'll see the spinners rotate now. When we looked at the pitch it has cracked a little. England picking up those three top order batters have done really well.
And that wraps up an eventful first hour.
Pakistan looked to be cruising when they wiped out their first innings deficit in no time. But Jack Leach took three wickets in six balls as Pakistan went from 53-0 to 54-3.
The hosts are effectively 20-3.
Pakistan lead by 20 runs
The Barmy Army trumpeter bursts into action as Ollie Robinson comes steaming in.
It is another funky field from Ben Stokes as he has a close circle of fielders in the off-side for the left-handed Saud Shakeel, who manages to pinch a single down to third man.
Alex Hartley
Former England bowler on BBC Test Match Special
Robinson will be looking to get some reverse swing from this ball.