Pellegrini admits the Premier League is a different level to the Bundesliga, where Haller scored 15 goals in 29 games last season, but he insists the forward can handle the step up.

"He does not have any problem about that," said Pellegrini. "In the two of three games I saw with him in pre-season, he is able to start without any problem.

"It's always difficult to change leagues. The German league is a big league but you have to make another step to arrive at the Premier League.

"It's a new league, with better defenders, a new way, but I think that in the way he continues working and playing as he did last season he will do well."

Haller should certainly get his fair share of goalscoring chances if, as expected, Pellegrini starts with a bold midfield of Jack Wilshere, Manuel Lanzini, Felipe Anderson and £25million signing Pablo Fornals against Manchester City.

"I can see them all playing together," added Pellegrini. "I can see playing with part of them. Or with Haller. Or with Albian Ajeti, Javier Hernandez or Michail Antonio. We have different options.

"That is not a problem for me as a manager. It is a problem when you do not have changes.

"We know in the Premier League you need 25 players. When you have more competitive options the players have better performance."

On their previous four visits to the London Stadium City have scored 17 goals and conceded just one, so West Ham will be hoping to catch the champions cold.

"I don't know if there is a good time to play Manchester City," admitted Pellegrini.

"But you have to play against them. We play here at home. We are not going to change all that we think about football because we play against them. We are going to try to play in the way that we play.

"They have good players. But we are not going to wait for them and lose to them by the least amount of goals that we can. We are going to try to play the way we do, we will try to win that game from the first minute."