The Montenegrin grabbed two goals on his home debut debut while the Ivorian contributed the latest in a series of strikes from free kicks as the hosts delighted the crowd at the Etihad Stadium.
"I think it's very important for Stevan," Pellegrini told reporters when quizzed after the game on how his new acquistion had settled in.
"He wasn't playing normally because he had some physical problems but, the last two weeks, he was working hard and I am sure he will be a very important player for us. I think he really played well in the second half but he moves more, he received the ball and I am very happy for him."
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"He is an excellent player but he adds goals from free kicks and last Sunday he scores again so I think, for him, it is very important to score goals," the Chilean remarked. "A player can always improve more and Yaya is trying to do that.
"Yaya stays normally and kicks the ball after we finish the daily work so he is really in a good moment but, yes, it is not normal for him to always score free kicks!
"He is a very important player for the team. I don't know what happened last year but I think he and all the players are playing with trust. I think it is very important."
David Silva has missed all of City's matches in September due to a thigh injury and, while Saturday's trip to Aston Villa may come too soon, Pellegrini is optimistic that his Spanish playmaker will be back sooner rather than later.
He added: "For next Saturday, I don't think he can play but maybe for next game in the Champions League he could be fit."