The 20-year-old Stockport-born City fan starred in City's 5-0 triumph over Burnley on Monday night, bagging two goals and crafting two more goals in a Man of the Match display.
Mahrez, who also produced an impressive two-goal performance, hailed the youngster's contribution and says he has high hopes for the budding England starlet.
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"Since I arrived, Phil has improved a lot," he told CityTV.
"He's been training with us and he's still young. He's been improving a lot.
"He has a lot of quality and he needs to keep going in a good way to improve more and more.
"He has a lot of time to improve and be a top player in this Club and the country."
Hear Mahrez's thoughts on Phil, his two-goal display and the overall performance in the video above...