Pakistan was all out on 304 against England in the first innings after Jack Leach destroyed the lower order on the first day of the last Test at National Bank Cricket Arena, Karachi on Saturday.
Pakistan captain Babar Azam was the highest scorer for Pakistan scoring 78 (123) before getting run out.
Rehan, an 18-year-old leg spinner, claimed Saud, who had scored 23 off 56, as his maiden Test wicket for England when Ollie Pope caught him at short leg.
The wicketkeeper-batsman Rizwan scored 19 runs off 24 balls quickly and attempted to take the game by storm, but he was caught by Ben Stokes at deep midwicket after hitting the toe of the bat off Root’s low full toss.
Earlier, retiring Azhar Ali appeared to be in excellent shape to make his farewell appearance on the crease memorable. However, his superb performance, which lasted 45 from 68 balls, was interrupted by a leg-side strangle from Robinson, with the original call being reversed by the TV umpire.
England, who are on their first Test tour of Pakistan since 2005, are ahead 2-0 in the series after winning the first game in Rawalpindi by 74 runs and the second in Multan by 26.