Shaw endured a torrid time against his England team-mate at the Emirates.
Saka had another brilliant game and put the Gunners 2-1 up with a sensational strike from outside the area.
Ferdinand has now criticized Shaw for giving the 21-year-old too much space to wreak havoc.
“I think Saka, my young player of the year, had Shaw scared. That’s the first time I’ve seen Shaw look like, ‘Oh, this guy has got my number’.
“He gave him far too much space a lot of the time, allowed him to run and get into the box before engaging with him because he didn’t want to get beat.
“He thought if he tried to face him up he’d just shift it round him. But Shaw’s been magnificent for United up to this point,” Ferdinand said.