Kompany has suffered a series of different muscle injuries over the past two years, raising concerns over his long-term fitness, but the club are confident he is ready to return.
Pellegrini said: "He is 100 per cent right, yes.
"He was injured when we played against Everton eight weeks ago, so maybe we waited a little bit more (for him) to come back to the team because the other times he was saying he was absolutely sure that he was 100 per cent but maybe he wasn't.
"We gave him one or two weeks more."
Kompany's organisational, leadership and defensive skills have been sorely missed and the significance of his return is acknowledged by Pellegrini, even if his praise for other defenders only occasionally slips.
He said: "He is one of the best. He is very complete in all senses.
"In one-v-ones, heading, he has a lot of speed, so he is very complete.
"But, I repeat, he is a very important player but we can play without Vincent Kompany.
"All of the last games we won without Vincent and we lost with Vincent against Aston Villa.
"I don't think this team depends on one player. We have other defenders, (Martin) Demichelis, Lescott, Nastasic, and they are doing very well also - or very bad sometimes - so we have a squad and now the return of Vincent is very important.
"But I repeat, in the last five (domestic) games, we just conceded one goal against Sunderland."
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