City left Tyneside fearing midfielder Samir Nasri, who was carried from the field on a stretcher after being felled by Mapou Yanga-Mbiwa's 75th-minute challenge, has suffered a serious knee injury.
Manuel Pellegrini said: "It's very serious. It was a very unfair kick and the player of Newcastle, it was directly a red card. I don't understand why he was not sent off.
"It's his medial ligament. We will see tomorrow how serious it is, but I don't think it's a light thing, I think it's a serious injury."