Pellegrini believes his side's performance proved they were back to the form which swept them to their second title last season
And captain Vincent Kompany is on the road to recovery.
Kompany missed the Sunderland clash with a hamstring strain and is also out of the weekend's game against Everton, but Pellegrini now hopes he could be back for next week's crucial Champions League clash with Roma.
"Vincent is improving and maybe it is not such a serious injury as we thought at the beginning - but he needs to see the whole week and we will see what happens with him," the Chilean said
Pellegrini watched his side hit back from conceding an early opener to Connor Wickham as the hosts looked to make it five straight home wins over City in the top flight.
Wickham's effort - a fortunate deflection off an attempted clearance by Pablo Zabaleta - came after Jack Rodwell had already come close to giving the Black Cats the lead.
But City swarmed back with the imperious Sergio Aguero hitting his 18th goal of the season in stunning style two minutes later before setting up City's second for Stevan Jovetic.
Zabaleta added City's third after the break before Aguero rounded off another stunning display with a fine individual goal to ensure City stay six points behind Chelsea in the title race.
Pellegrini added: "I think we are returning to the performances we had last season
I think if we continue playing this way, of course, we will fight for the title, but I think three or four other teams will also be there
"(Aguero) is an important player but it is not just Sergio Aguero - we play in a way that it is very useful for him to score but it is important for him not just to think about scoring but to play for the team
"There are a lot of good strikers but I said before the last game that I am sure he is one of the best five players in the world because he is not just scoring - he is playing very well."
Sunderland boss Gus Poyet admitted his side could have no complaints about the manner of City's victory, but rued his team's inability to hold onto their early lead for more than two minutes
Poyet said: "I can't have too many complaints - they were better than us in every aspect of the game
We started well and had a chance before we scored our goal, but then Aguero appears from nowhere and does something special."
Source : PA
Source: PA