City will go into the 2019-20 season as favourites to win the league for the third straight year, and they edged Liverpool on penalties in the Community Shield on Sunday.
"I think United with Maguire and the other players they bought, Arsenal as well, Chelsea and Tottenham, they won all of their pre-season so I think there will be many, many contenders this time," he told a news conference on Sunday.
"But I think Liverpool... we were so happy when we realised which team we were going to face for the rest of the season, they are the champions of Europe, that's why I gave a lot of credit to our victory today.
"The way we played, particularly in the first half, and the way we defended, but they are a top-class team. The difference can be one point ahead, one penalty ahead, that is the difference, it's minor.
"Sometimes a call will come on your side, sometimes not, that's why it's good to face them, this is the team we are going to face this season.
"This is how well prepared we have to be until the end to try to win the titles."
Manchester City begin their league campaign at West Ham on Saturday, with the Hammers among the teams expected to impress this year after their purchase of players such as Sebastien Haller and Pablo Fornals.
Following the West Ham game, they face an early test against one of their title rivals as Tottenham are the first team to travel to the Etihad.