Recent slip-ups by the Londoners saw them get thrashed at Chelsea 6-0, before drawing 2-2 at home with Swansea City, and Pellegrini is hungry to completely kill off Arsene Wenger's hopes of breaking his league drought.
"I think that if we win on Saturday we can be 12 points on top of Arsenal if we win the two games that here we have in hand," he said.
"It is an important difference. Six points is also an important difference.
"It is a match of six points but it is not the last match and not the match that will decide the title.
"It is a huge step to continue in the way we are doing so far. Yes, of course it is a big game because it is against a team that is fighting for the title also."
Arsenal are only six points off top side Chelsea, but with the caveat that City - three points adrift of the Blues in third - have two games in hand.
A portion of Pellegrini's squad were involved in City's thrilling league win in 2012, and the Italian noted the likes of Sergio Aguero, David Silva, Yaya Toure, Joe Hart and Edin Dzeko as experienced title winners in England that would help their cause in the run-in.
"It's important to have the experience to win titles. A lot of things can help but the most important thing is the performance of the players in the last few games," he said.
"This is a different moment, there are different players. The most important thing is the present, the next game.
"To play in the same way we did (against Manchester United) in the next game."
On Toure in particular, Pellegrini said: "I think he's had a very good season so far, we hope he can continue. Hopefully we win the title and he can be the best player.
"I don't want to compare him with anyone – both of them have had amazing seasons so far. But they must try to finish the season in the same way. And after that it will be the same as the fight for the title."
