Benitez, while disappointed at his side's failure to take advantage of Manchester United's surprise loss at West Ham, conceded City are becoming a formidable unit under Sven Goran Eriksson Eriksson.
"Manchester City are getting very close to a top-four team," he said.
"I was talking with Dietmar Hamann beforehand and he told me they have some good players, as you could see. You cannot win nine games in a row at home without having good players.
"They should be really close but the question in this league is whether you can keep your team playing well for a long time. The season lasts nine months and it is hard work."