England are monitoring the fitness of Ben Duckett after the opener sustained a suspected dislocated thumb on his left hand while fielding on the second day of the opening Test against Pakistan, forcing him to sit out the start of his team’s first innings.

Sources within the England camp said they were optimistic that Duckett would be fit to bat at some point on Wednesday after resting the injury overnight, but though there were no immediate plans to send him for a scan his condition will need to be fully assessed once any swelling subsides. The team can scarcely afford to lose a key player, needing all the batting depth they can muster as they attempt to overhaul Pakistan’s first-innings total of 556.

Related: Crawley and Root rebuild after Duckett blow and Salman Agha ton for Pakistan

With Zak Crawley, England’s other first-choice opener, having just returned from a broken finger also sustained while fielding at slip, Ollie Pope stood in for Duckett and was dismissed for a duck as the tourists’ reply got off to a dismal start. But Crawley, with a run-a-ball 64, and Joe Root, with 32, took England to 96 for one at the close, still 460 behind, as the team tries to recover from the best part of two hot and draining days in the field.

“They were immensely tough conditions for everyone out there,” said Brydon Carse, who dismissed Naseem Shah and Aamer Jamal for the first two wickets of his Test career.

“It’s been tough over the last two days. Obviously it’s draining in the heat, and we didn’t get much out of the wicket. But credit to the team and everyone who kept coming back each session. It’s an incredible environment in there, and the guys keep smiling, keep joking, and keep trying to give their best each session. There’s some tired bodies in that camp at the moment but the lads will rest up and come again.”

The pivotal moment of the day came when a brilliant, juggling catch by Chris Woakes on the boundary was ruled out because a foot was brushing the turf on the wrong side of the padding as he collected the ball. “It was a great bit of fielding, but one of those 50/50 chances that just didn’t go our way,” Carse said.

The reprieved batter, Salman Agha, went on to score an unbeaten 104, having been on 15 at the time of the incident. “Initially I did think it’s out, and I was walking to the dressing room,” Salman said. “To score a hundred things have to go your way, and you can say it was my day.”

Salman proved particularly adept at nursing the tail, hogging the strike as he hit 10 fours and three sixes to take his team’s score from 393 for six when he came to the crease to an ultimately daunting total. “I have been doing this for two years now so I have an idea what you need to do when the tail comes,” he said. “It was pretty normal stuff for me. When the tail comes it brings the best out of me, you can say that.”