Chelsea have a three-point lead over defending champions City at the top of the Barclays Premier League and are rated as favourites for the crown.
But City trailed the Londoners by eight points just three weeks ago and have found form with seven successive wins – in all competitions – after a difficult spell in October and November.
That gives Pellegrini plenty of hope as he remembers how Arsenal’s challenge faded last season.
This time a year ago the Gunners were top while City were fourth. Those positions were reversed by the end of the season as Arsenal faded in the second half of the campaign.
Pellegrini said: “I think Arsenal last season had a very similar number of points last season as Chelsea have now at this moment.
“So we’ll see what happens in the second half and how many points you need to win.”
There is a general feeling that the current Chelsea side are made of sterner stuff than the Arsenal team of 12 months ago but Pellegrini says there are no certainties.
The Chilean, speaking at a press conference, said: “We don’t know. Maybe Arsenal last season couldn’t do it in the second half but we don’t know what Chelsea will do this year.
“I think that we must try and think about our team and not the others.”
City and Chelsea do look to be the strongest two sides in the competition but Pellegrini believes other clubs could yet challenge.
Manchester United, after a poor start to the campaign, have noticeably climbed into third place after a strong sequence of results in the past month.
Asked if United were realistic challengers, Pellegrini said: “Of course. I said six or seven weeks ago that you cannot say that Chelsea are the only club that can win the title.
“There are a lot of clubs who, for part of the season might not have been playing well, but after that they can win six, seven, eight games in a row and be fighting for the title.
“It is not only Manchester United, one of the other important clubs could have a brilliant second half of the season and also be fighting.”
Pellegrini has been pleased with the turnaround in his side’s fortunes after questions were starting to be asked of their fortitude in early November.
City won just one in six prior to the last international break but have hit form since, winning five straight in the league and qualifying for the Champions League last 16 with exhilarating victories over Bayern Munich and Roma.
City now have 36 points, three games short of the halfway stage – a key landmark in Pellegrini’s planning.
He said: “Normally you need at least 41 or 42 points, especially in this season with Chelsea winning so many points, if you want to be fighting for the title.
“It is important to try and continue winning the games in the way that we have been so far, especially in the last month.
“We will see at the end of the first round how many points we can win.”