In form Manchester City midfielder has been ruled out for up to a month with a calf injury sustained during their 5-2 victory over CSKA Moscow at the Etihad Stadium on Tuesday.
The Spain International has been in goalscoring form in recent matches with three goals from seven starts but may now may miss as many as five games.
The loss of such an in-form orchestrator for City’s midfield will be a blow but could be an opportunity for James Milner or Jesus Navas to stake a claim for a run in the first team after excellent performances by Silva and Samir Nasri kept them on the sidelines in recent weeks.
Silva, 27, could be fit to return for City’s game at Southampton on December 7.
Pellegrini could have captain Vincent Kompany, injured for several weeks with a thigh strain, back in time for the home game against Tottenham on November 24.