Root won the toss and opted to bowl under an overcast sky in Leeds on Wednesday.
Both teams have been in underwhelming Test form, with England winning just two of their last 10 matches to start a new era without ex-captain Ben Stokes and coach Brendon McCullum.
Root is back for a second stint as captain, Marcus Trescothick is interim head coach before Stephen Fleming starts full-time in the role in December, and Dan Lawrence - a batter but also a spin option - is in at No 6 in his first Test in two years.
Jordan Cox will bat at No.3 in place of the injured Jacob Bethell, while Ollie Robinson got the nod to join a pace attack also containing Jofra Archer, Josh Tongue and Gus Atkinson.
Pakistan have won just one of their last nine Tests and are without captain Babar Azam, who hasn't recovered from a finger injury.
Salman Agha deputises as skipper and batter Shan Masood is back - at No.3 - after a broken finger.
Pakistan have not won a Test series in England since 1996.
There were some clouds before the toss, and the forecast is for some rain and sunshine later on Thursday.
Teams: England: Ben Duckett, Emilio Gay, Jordan Cox, Joe Root (capt), Harry Brook, Dan Lawrence, Jamie Smith, Ollie Robinson, Gus Atkinson, Jofra Archer, Josh Tongue.
Pakistan: Azan Awais, Imam-ul-Haq, Shan Masood, Abdullah Shafique, Saud Shakeel, Mohammad Rizwan, Salman Agha (capt), Ali Usman, Khurram Shahzad, Mohammad Ali, Mohammad Abbas.
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