The two teams started the highly anticipated encounter locked together at the top of the standings and City looked set to beat Juergen Klopp's Liverpool when Mahrez ballooned his spot kick way over the crossbar, after substitute Leroy Sane had been brought down by Virgil van Dijk.
Guardiola admitted after the game that his team were deeper than usual as they controlled Liverpool's rapid forward line expertly. Their century haul of points last season has ensured expectations remain incredibly high this term but simply retaining the title for the first time - something no club has managed for a decade - would be achievement enough.
Statisticians analyse a wide range of shots from Premier League history and, based on factors including the distance from goal, the angle of the shot and the type of opportunity it is, they are able to assign an xG value (expressed as a percentage) to every attempt to determine just how good a chance it is.
But they have survived their first big test this season, coming through a gruelling run of seven games in 22 days against some of the toughest teams in Europe, including Paris St-Germain.
You have to go further down the table to find Manchester United in eighth place and, much like Arsenal, I do not see them as title contenders at all. You need to finish. We have played City often and they are outstanding. "We've had some hard games but we will continue".
While he has been impressed by their, he reckons Sarri's side are too reliant on Eden Hazard, who scored his ninth goal of the campaign in the 3-0 victory over Southampton on Sunday.
"For both teams it was really intense, and both showed respect for the other team". Don't lose the ball in the wrong moment, otherwise you have a big problem.
"Both teams did well, and we were a bit lucky with the penalty of course".
"I think to keep a clean sheet after a penalty in the last five minutes makes me a very happy man".
"After the worldwide break there are three important games against Huddersfield, Red Star and Cardiff so we want to be ready for that".