The 25-year-old has not made a Premier League appearance this season despite encouraging pre-season form.
Ahead of the game against Sinclair's old club Swansea, Pellegrini said: "We have a squad.
"Scott knows perfectly what his place is in the squad.
"He must work every day and the moment I think he is better than the players we have, he will have a chance. All the players have a chance to change the mind of the manager. That just depends on the way I see him or anyone works in the week.
"Maybe he had the chance also to go on loan at the beginning of the season. He decided to stay here. I don't have any problem."
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