Phil Foden netted an impressive FA Cup brace in Manchester City's 4-1 fifth-round win at Newport County despite a Rodney Parade pitch he branded the worst he has played on.
Pep Guardiola's free-scoring Premier League leaders were kept at bay during a keenly contested first half before Leroy Sane broke the deadlock six minutes into the second period.
Foden dispatched a fine solo effort in the 75th minute but the 18-year-old's fifth goal of the season was required to settle nerves a minute from time after Newport striker Padraig Amond reduced the arrears.
"We showed our professionalism, keeping the ball moving. In the end it showed," the England Under-21 international told BT Sport.
"We scored straight away after [Amond] scored, it's always good to do that.
"[The pitch] is the worst I've played on, to be honest."
"The most important thing at the end is the result. If you can add the performance, it's perfect," Mahrez told BT Sport.
"It wasn't a good pitch but we are professional. We have to adapt to everything. Everyone is happy to be through to the quarter-finals."
Next on the agenda for City is a Champions League last-16 trip to Schalke on Wednesday before they take on Chelsea in the EFL Cup final.
However, Mahrez was quick to dismiss a question regarding his team-mates' capacity for completing a clean sweep of major honours.
"Now we forget the FA Cup, we have to concentrate on the Champions League," he added.
"We are just taking it game by game. It is dangerous to project yourself too far."
