Zimbabwe in place of the injured Shadab Khan.
Shadab was ruled out of the tour against South Africa due to a toe injury that he sustained in the second ODI against South Africa on Sunday.
After the completion of the four-match T20I series against South Africa, Pakistan will travel to Zimbabwe for a three-match T20I series.
Zahid was originally named in the two-Test squad against Zimbabwe, while Fakhar was initially named for the ODIs.
The Pakistan Cricket Board said both the changes were approved by the national selection committee on the request of the team management.
Zahid made his T20 debut in the last T20I that Pakistan played against South Africa at home in early March but was surprisingly included only for the two Tests against Zimbabwe.
The members of the Test squad will fly out to join the team mid-April.
Fakhar Zaman in red-hot form
On Wednesday in the third ODI, Pakistan’s Fakhar Zaman brought up his 2nd successive hundred against South Africa at the SuperSport Park in Centurion.
Fakhar Zaman hit his 6th ODI hundred in the crunch series-decider between South Africa and Pakistan. The opener was in complete control of his knock from the word go after South Africa won the toss and put Pakistan in to bat.
Fakhar Zaman hit as many as 3 sixes and 9 boundaries for his 104-ball 101. This was the first time Fakhar has hit back-to-back ODI hundreds in his career.
Notably, the Pakistan opener becomes only the 3rd visiting batsman after Kevin Pietersen in 2005 and Joe Root in 2016 to hit back-to-back ODI hundreds in South Africa.
2nd Test, Birmingham, 10-13 Jun 2021
1st Test, Gros Islet,10-12 Jun 2021
3rd ODI, Utrecht, Jun 7 2021
1st Test, London, 02-06 Jun 2021