The striker returned from injury in the 2-1 defeat at Arsenal last week, but was substituted shortly after the hour mar.
The 27-year-old was then benched for the 4-1 over Sunderland, before starting Tuesday's 0-0 draw with Leicester City, but again failed to complete 90 minutes.
However, Pellegrini has backed his top scorer to come good and says it's natural that his performance levels have dipped given his recent physical problems.
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"I never talk about individual performances because we are a team. We know, because we know him and after all this year he needs two or three games to return to his normal performance.
"He needs these minutes. I don’t want him to play more than 65 or 67 minutes.
"It will be very useful to see the best Kun in the first round of the second half of the season."