West Ham captain Mark Noble is expected to miss Saturday’s trip to Arsenal.
Manager Manuel Pellegrini says the long-serving midfielder has a back problem which has prevented him from training this week.
It follows speculation that Noble could be left out following the Hammers’ poor start to the season.
Last weekend Pellegrini mentioned that many fans had left the London Stadium early during the 2-1 defeat by Bournemouth, and he moved to clarify his comments at his pre-match press conference on Thursday.
He said: “It’s not a criticism of the fans, it’s how much the team needs them.
“I perfectly understand if you are losing four or 5-1 then you might leave early to go to your house but at 2-1, we need all of us to be together. Everyone.”
With nine new signings to incorporate, Pellegrini needs to settle on his preferred line-up sooner rather than later.
But he insisted: “You never have a starting XI. It is difficult because you have to play so many games and you must change it.
“You must involve the whole squad and chose the best moment for each game. But after that game you will have another problem and can’t play that team again.”