Crawley out without scoring in first over
Four wickets for Leach as Pakistan bowled out for 304
Leg-spinner Ahmed, 18, takes two wickets on debut
Babar makes 78 before being run out by Foakes' smart work
Image source, Getty ImagesAhmed is chewing away on some gum, confidently pulling up the sleeves of his shirt after each delivery. He's got a growing beard on his chin too. Not bad for an 18-year-old.
One ball is too short and Azhar whacks it away. The rest of the over is nicely pitched, drawing the Pakistan veteran forward.
Daniel Norcross
BBC Test Match Special
Rehan Ahmed's first two balls have some flight.
It's a big moment for English cricket too. Rehan Ahmed is the youngest man to play cricket for his country.
He bounds in and gives his first ball plenty of loop. First one ticked off.
Don't worry, Ruth. Jimmy Anderson is old enough to be Ahmed's dad and he's still playing for England.
It's time. 18-year-old Rehan Ahmed is taking off his cap. The camera immediately pans to his actual dad up in the stands.
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I wasn't doing anything special in 2004, but the realisation that I'm old enough to be Rehan Ahmed's grandmother has both depressed me and also made me very excited about the future of England cricket. Go well young man (as the youngsters would say).
Ruth Brooksbank, Bradford
Wood responds with one that this time whizzes past Babar's grille. It takes a lot of effort to get the ball up there.
There's more arm-waving from Rehan Ahmed. His big moment is not far away.
Waqar Younis
Former Pakistan fast bowler on TMS
Magnificent shot! Babar is not happy with the England bowlers trying to threaten them with the short balls. That was an angry shot.
Mark Wood is going to continue the bouncer ploy we have seen all series...
Thwacked by Babar! He did not like that. Four runs.
Waqar Younis
Former Pakistan fast bowler on TMS
Babar has got to be sensible here with Wood bowling.
Good news for England. Ollie Robinson is back on the field.
Rehan Ahmed just teased us by wandering in, looking as if he was going to bowl. Wood continues.
Waqar Younis
Former Pakistan fast bowler on TMS
Image source, Getty ImagesBabar loves this ground. The last time he played here he scored 196 against Australia. That's probably his best innings I've seen. He batted so beautifully.
Azhar 5, Babar 0
Mark Wood has a smile on his face, that wicket having maybe earned him one more over.
Babar Azam is out there after 70 minutes of play. The Aussies are 33-3 too. I can sense England fans smiling from under the covers.
Simon Mann
BBC Test Match Special commentator
The plan has worked! Masood went for the pull shot and England are delighted.
Masood c Leach b Wood 30 (Pak 46-2)
As soft as you like! A Mark Wood bouncer hardly gets to waist height and Shan Masood, who had looked really good, tries to pat it around the corner with the fielders all lurking in the deep. The ball hits the top edge, maybe even the back of his bat, and it loops to Jack Leach at fine leg.
A really rubbish way to get out.
Image source, Getty ImagesMeanwhile Bangladesh have resumed their unlikely chase of 513 against India in the first Test at Chattogram.
Resuming on 42 without loss, openers Zakir Hasan and Najmul Hossain Shanto have added 77 to their overnight total to reach 119-0 at lunch on the fourth day. You can keep an eye on that match here.
Jack Leach has the one wicket so far but you wouldn't say he has bowled his best.
Azhar gets his first boundary by guiding him well off the back foot.
Time for a drinks break.
Image source, Getty ImagesEngland return to Karachi in this Test, the scene of one of their most famous overseas Test wins.
22 years ago, England won the final Test against Pakistan to take a three-match series 1-0. It was only their second ever Test win in the country, and Pakistan’s first defeat at Karachi.
Nasser Hussain and Michael Atherton, who were captain and opening batter that day, have been reminiscing about that famous Test match win on BBC Sounds with TMS's Simon Mann.
After we get back under way, Shan Masood pulls one with expert precision from in front of his chest. Wood throws his hands up, suggesting he nearly had his man. Ben Stokes puts his hands onto his head. It looked a perfectly played shot to me. Maybe a bit of an attempt to get into the batter's head.
Masood has 30 from 34 balls.
Vic Marks
Former England spinner on BBC Test Match Special
It has been a very enterprising start from Masood. It's a completely different game when Leach is bowling to right-handers.
Azhar's body has taken a beating in this series. He was badly hit on the finger in the first Test and now looks to have taken one on the arm from Wood.
Out comes the physio.
Ollie Robinson is struggling with an upset stomach, we're told.