City currently sit top of the table after securing 38 points from 15 games with local rivals United just two points behind on 36, while Spurs sit in fourth on 31 with a game in hand on all top-half sides.

Although not dismissing the possibility of Arsenal, Chelsea or Liverpool lifting the league trophy in May, the Italian coach feels Sir Alex Ferguson's Red Devils and Harry Redknapp's Spurs represent the greatest threat to their bid for glory.

"At the moment, us, United and maybe Tottenham are the three teams that can fight for the title," the former Inter boss told reporters.

"But the season is long. Chelsea, Arsenal and, maybe, Liverpool could also try. The season is hard. We have a lot of games to play in the next 40 days."

City were handed a tough draw against Porto in the last 32 of the Europa League on Friday, and with both sides knocked out of the Champions League by finishing third in their respective groups, Mancini admitted the Portuguese outfit will be troublesome opponents.

The Blues boss added: "Manchester City against Porto feels like a Champions League game, it is probably the toughest game we could have had."

"I have come up against them as a player before and also a manager, they are a very good team and a very strong club in Europe."

"They are used to playing in Europe, in a great stadium. Not too many years ago they won the Champions League and also won the Europa League last year. So they are a strong team."

"It will be a hard match for us. We know this game will be difficult, but also it will be difficult for them."

"It is a good game for the fans, a big team coming to Manchester, and we will be looking forward to it."

City host fifth-placed Arsenal on Sunday, six days after losing 2-1 against Chelsea at Stamford Bridge, with Frank Lampard's late penalty securing victory after Gael Clichy's second-half sending off.

"Sooner or later, this had to happen, what happened against Chelsea," Mancini said.

"With 10 players it was difficult and if we didn't only have 10, we wouldn't have lost. But that is it, this is football."

While City have won all seven games at the Etihad Stadium this season, Mancini admits that Arsenal striker Robin van Persie may prove a threat, and compared the Dutchman to his forward trio.

"Van Persie is an incredible player. He is like (Sergio) Aguero, (Edin) Dzeko, Mario (Balotelli) - scoring a goal every game," he said.

"At this moment he is very good, like Arsenal. At this moment they are playing very well."