Many supporters were surprised when Mahrez was named amongst the substitutes at Carrow Road, as the winger has been in scintillating form so far this season.
However, Ranieri revealed that he took the decision as he wanted to use the tricky winger as an impact sub, and his decision paid off, as Leicester picked up a 2-1 victory.
"I left Mahrez out because I wanted to put him on in the second half, but the match was different and it was good for us, and for Mahrez to get a rest for one match," said Ranieri, quoted in the Leicester Mercury.
"It is okay, he can never play 38 matches. I have a lot of players in good condition and that is very good for the manager."
Mahrez ended up being an unused substitute in the fixture, as Ranieri utilised other options off the bench ahead of him.
It may have been disappointing for the Algerian, but Ranieri always has had a reputation as a manager who likes to alternate his sides, and it should ensure that the winger remains fresh for future matches.
Leicester return to action in two weeks' time when they take on Southampton, and Mahrez will be hoping to be back in the starting line-up for that contest.