Algerian midfielder Mahrez responded in the perfect way to his penalty miss at Liverpool last time out by producing a man-of-the-match display and registered his first goal at the Etihad with a delicious second half shot that curled past former City keeper Joe Hart.
And Guardiola hailed Fernandinho’s performance as ‘extraordinary’ after the Brazilian's defensive midfield master-class was capped by a thunderous-struck third goal.
With Sergio Aguero, Bernardo Silva and Leroy Sane also on target, it rounded off a perfect afternoon for the Blues – especially with Kevin De Bruyne making a welcome return to action after two months out injured.
In praising Mahrez, the City manager said: “In Anfield, he played so good… that’s why he played today.
“He played with personality. Only the takers can miss a penalty. He scored a great goal, but the assists he created, how aggressive he was, was so good.
“Riyad made a good performance. We knew he was a talented player. He’s a guy who likes to play with the ball. He goes to the byline, can score with left or right.
“He’s a good signing for us.”
The City manager was equally full of praise for Brazilian midfielder Fernandinho.
Pep has previously described the Brazilian as a ‘gift’ and he claimed the 32-year-old’s display this afternoon was his best yet this season.
“Fernandinho in the period we are together, he is so important for us. No doubt about that,” Pep added.
“Today he was clever, his body shape, every time he received the ball he was ready for it. He was incredible – extraordinary.
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“Today was one of the best performances this season. He is a key player for us.”
It was City’s most emphatic result of the season and ensured the champions retained top spot in the Premier League.
And Guardiola said City’s superb level of performance was as a direct result of how comfortable his players felt – especially at the Etihad.
“Our level at home especially is so high, we’ve won every game at home and played well,” Guardiola added.
“We attack well, five different players scored today, so not all the pressure is on Sergio and Gabriel.
“We learn every day, we attack better when they defend deeper. When teams attack us, we have guys with a lot of pace.
“We feel comfortable at home, with our people on our side. The pitch, thank you for groundsman, they help us to play quicker.
“Even when we rotate players, we can keep going and be consistent in the Premier League, and that is so important.”