The fixture between the two title rivals is the Premier League's early kick-off on Saturday, and comes just three days after Arsenal's 2-0 defeat at Napoli in the UEFA Champions League.
By contrast, City claimed an excellent 3-2 win at Bayern Munich on Tuesday, meaning they have had 24 hours more in which to prepare.
But Pellegrini does not believe that will have any impact on the outcome of the game, and urged his side to cut the six-point gap to the leaders in half.
"For Arsenal and our team, this is a very important game," he said. "They played one day after we did in the Champions League.
"Maybe our match was not exactly the same but I don't think that will be an advantage or those things will decide the game. I think the way both teams will play will be more important.
"We need to be at least three points near the top. All the teams, especially if we win, will be near us. There are six or seven teams fighting for the title.
"This is our opportunity to take three important points against the best team in the Premier League at the moment."
The Chilean also refused to rule Manchester United out of the running for the league crown, despite David Moyes' men falling 13 points adrift of Arsenal after back-to-back 1-0 home defeats to Everton and Newcastle United.
He added: "They have good players and (a good) manager. They have the second half of the Premier League to play and a strong team like them will always have chances."
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