The Algerian struck our second goal of the evening, after goals from Erling Haaland and Fabio Carvalho had the score level at the break.
Mohamed Salah levelled again before Nathan Ake headed in the winner just before the hour mark to send us into the quarter-finals of the tournament.
The encounter marked the return of competitive domestic action for Pep Guardiola's men after a 40 day break due to the World Cup, and Mahrez was delighted with the display from all the City players.
"It's a great win against a tough opponent, it wasn't easy," he reflected.
"I think we did a good game and deserved to win in the end. It's never easy like I said.
"They're a very good opponent and we were very good today. After all that time off, we were on it!
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"And like I said, we deserved to win."
The winger also touched on our hopes for the remainder of the competition and for the second half of the season.
Watch the entire interview via the video at the top of the page.