Kompany was forced off at half-time during last weekend’s 4-2 defeat to United at Old Trafford and boss Manuel said: “He has a muscle injury – we don’t know how long. We don’t know if he will be fit before the end of the season.
Pellegrini also revealed that he welcome back Dedryck Boyata back to his squad against the Irons but cannot select Stevan Jovetic, Wilfried Bony, Gael Clichy and James Milner due to injury.
However, the Chilean boss said: “Every time you manage an important club if you don’t have the results that the club deserves everybody is talking about changing the manager,” he said.
“I trust a lot in the work I do. Nobody is happy with the results, you can’t be happy when you are out of the fight for the title.
“We are thinking about the next game, the game we must play against West Ham on Sunday.”