Six days on from their 4-1 derby demolition of rivals Manchester United, City led twice before spurning the chance to go top of the table as they suffered a dramatic 3-2 loss at Aston Villa on Saturday.
In any event, a City victory would only have briefly placed them at the summit after Arsenal – who lost to Villa on the opening day following a fraught pre-season – chalked up a fifth consecutive win at Swansea City to set the pace after six matches.
Pellegrini's side, who also went down 3-2 to newly promoted Cardiff City in August, are five points off the pace in fifth position – one place behind Southampton and seven above rivals United, who slumped to a shock 2-1 reverse against West Brom at Old Trafford.
Nevertheless, the Chilean is unruffled by the prospect of the most open title race recent memory, putting such surprise results down to the league's natural competitiveness.
"I think the Premier League is very regular," he said. "I don't know how many teams will be fighting for the title because we are just starting.
"It is a very tough league and the differences between teams are not too much."
Yaya Toure's sixth goal in eight matches and a second-half header from Edin Dzeko were not enough for City at Villa Park as Karim El Ahmadi and Leandro Bacuna took turns to restore parity before Andreas Weimann capitalised on some haphazard defending to poach a 75th-minute winner.
Following that, his Cardiff experience and a scarcely deserved goalless draw at Stoke City, Pellegrini is all too aware of the threats posed by the Premier League's so-called lesser lights.
"Of course it is something that I know and something that I see every week" he added. "It happens.
"We are just starting working and we hope that we will improve in the future so we can win the games we must win.
"We are not thinking about the title at this moment. We are thinking about winning the most amount of matches. In the Premier League the differences can be very small.
"So we can't know what will happen in the month of May but, playing the way we are playing, I am absolutely sure that we are going to be fighting for the league."
