The City captain believes that the 36-year-old can be a key player for Manuel Pellegrini's side, and has already been impressed with what he's seen from his teammate in training.
"I think all of the signings will make a big difference," Kompany told reporters. "Just watching Frank Lampard in training for example.
"People won't tip him as one of the players to make the biggest difference for us this season, but he looks amazing, unbelievable."
Lampard, who was released by Chelsea at the end of last season, will stay with the Premier League champions until January before linking up with new MLS side New York City FC.