England 232 for 2 (Duckett 80*, Root 72*) trail Pakistan 556 (Masood 151, Salman 104*, Shafique 102, Shakeel 82, Leach 3-160) by 324 runs

He added one more single before the interval, to reach 72 not out - his 99th fifty-plus score in Tests, with a golden opportunity to celebrate his latest landmark with a 35th Test hundred and a fifth of another stellar year.

Meanwhile, Duckett's participation in this innings had been in some doubt when he left the field clutching his thumb in agony after taking the final catch of Pakistan's innings late on the second evening. But, after receiving treatment overnight, he strode out at No.4 to rattle through to a 45-ball half-century, his fourth against Pakistan.

It was a session of ominous toil for Pakistan, who found a hint of reverse swing late in the session but found next to no assistance from a pitch that is showing no signs of any deterioration after almost 200 overs of action.

Their one breakthrough in the first hour was a case of batter error. Crawley had looked distinctly threatening in the opening overs, particularly on his trademark drives, but then he flicked uppishly across a full length from Shaheen Shah Afridi and picked out Aamer Jamal at midwicket. Jamal's second catch of the innings wasn't a patch on the screamer with which he had dismissed Ollie Pope on the second evening, however. The ball looped straight to him, and he all but dropped it before scooping it up at the second attempt.

Either way, Crawley was gone for 78 from 85 balls - his sixth score between 60 and 80 this year - and at 113 for 2, Pakistan had a glimmer of an opening. Duckett, however, took it upon himself to slam that window shut with a calculated assault on the spinner Abrar Ahmed.

Showing no ill-effects from his thumb injury, Duckett climbed through a slog-sweep for his first boundary then thumped the over-correction through the covers for another four, and when he cracked three more fours in a single over to bring up England's 150, Abrar retreated from the attack with the bruised figures of 9-0-68-0 - though he did return for three tidier overs later in the session.

Duckett had one clear life on 37, when Naseem Shah found his outside edge only for the ball to bisect keeper and a wide first slip. Root, however, was his typically unflappable self as he settled back into the accumulatory rhythm that had been a feature of his form this summer. Hard though Pakistan toiled, they burned through two reviews late in the session, one apiece for each batter, to compound their struggles for penetration.