City's recent form has earned plenty of plaudits while Newcastle have had a difficult past fortnight, but Pellegrini sees no room for complacency.
Rampant City are unbeaten in 14 matches stretching back to November, and hit six past West Ham in midweek, while the Magpies have lost their last three in all competitions.
But Alan Pardew's men remain eighth in the Barclays Premier League, 11 points behind City but just six off a Champions League spot.
Pellegrini said: "Of course it will be a real fight.
"Newcastle in the last two games have lost, but when they lost against Arsenal one or two weeks ago they were playing very well and they were fighting for the first position in the table.
"In the FA Cup they lost at home against Cardiff but I am sure that playing at home they will be a very difficult team."
City's demolition of West Ham at the Etihad Stadium on Wednesday, which all but secured a place in the Capital One Cup final, was merely the latest in a growing list of emphatic home victories this season.
Arsenal conceded six at Eastlands, Tottenham were thrashed 6-0 and Norwich 7-0. Champions Manchester United went down 4-1 after another rousing display while Newcastle themselves lost 4-0 there on the opening weekend.
Pellegrini, however, has warned of the dangers of reading too much into those scorelines.
He said: "It always seems the opposition are not very good when you score so many goals but, I repeat, there are no easy games in the Premier League.
"Maybe when you finish the game you might think it was easy because we played very, very well, but not all the games will be exactly the same.
"Maybe playing exactly the same we might score only one or two goals. It is very important to improve in all senses as a team."
Striker Alvaro Negredo's hat-trick on Wednesday took his tally during an impressive first season in England to 18.
His performances, alongside Edin Dzeko, have made light of the absence of Sergio Aguero over the past four weeks, although the Argentinian remains top scorer with 19.
Newcastle boss Pardew has likened the Spaniard to Alan Shearer and Pellegrini certainly hopes he maintains his form.
He said: "We will see in the future but I think Alvaro played very well also with Aguero, and has for the whole season, and we hope in the future he will continue the same way."
City have already scored 92 goals this season and have a good chance of reaching a century before the end of the month, as they chase glory on four fronts.
Records do not interest Pellegrini but he would be happy to take them.
He said: "No, but if we can break the records, no problem.
"I just want to have a good team, playing the way I want and with that team, to win titles."