The former Chelsea star, having signed for New York City FC this summer, is set to join the Premier League champions until mid-January.
Though he would not be available for the knockout stages, to which City are relative newbies, Nasri believes the England international's extensive European pedigree should benefit Manuel Pellegrini's side immensely.
"We'll particularly benefit from having [Lampard] in the Champions League because that's where we need to improve this year," the Frenchman told reporters.
"He's a great player and any team would benefit from his experience. He's won it and I think he can help us. It's good that he's an English player, too, and we've had a little problem with that."
Lampard's temporary switch is expected to be officially confirmed imminently, with Pellegrini having announced the agreement on Saturday.