Joe Root broke Alastair Cook's Test runs record on the third day of the opening Test against Pakistan in Multan on Wednesday, as he helped guide England to 232-2 at lunch.

The 33-year-old became England's highest run scorer in Tests, and the fifth highest of all time, when he drove Pakistan seamer Aamer Jamal for a straight boundary to reach 71.

At the interval, Root was unbeaten on 72 having faced 118 deliveries while Ben Duckett was on a rapid 80 off just 67 balls.

Left-hander Duckett was showing no ill-effects from the thumb he dislocated in taking a catch on Tuesday that had forced him to come in at number four instead of opening the batting.

England, who rattled along and scored 136 off 25 overs in the session for just the loss of Zak Crawley, who made 78, trail by 324 with eight wickets in hand after Pakistan made 556 in their first innings.

It was a day to remember for Root, who took 268 innings and 147 Tests to go past his former captain Cook's total of 12,472 runs from 161 Tests in a glorious career that ended in 2018.

Root has so far knocked five fours and Duckett has found the boundary 11 times in an unbroken stand of 119, while Pakistan wasted two of their three reviews as they searched for a third wicket.

Root also added 109 for the second wicket with Crawley, who hit 13 fours in an 85-ball stay but departed early on the third morning.

In the fourth over he failed to keep a flick down off pace bowler Shaheen Shah Afridi and was caught at the second attempt by Jamal at mid-wicket.

Duckett started with trademark aggression, taking five boundaries off spinner Abrar Ahmed and completing his 10th Test half-century off just 45 balls.

It enabled Root to accumulate steadily at the other end as he brought up his 65th Test fifty off 76 balls before being applauded by a handful of England fans and teammates in the dressing room when he broke Cook's record.

Root, who made his Test debut in 2012, went to the lunch interval with the new record standing at 12,474 runs and counting.

The all-time list is headed by India's Sachin Tendulkar with 15,921 from 200 matches.