Grealish will not substitute Mount if Mount plays in a CAM role. But Grealish will play ahead of Mount in Southgate set up where the winger constantly change his position going down Striker or changes his position from MF and wing. I.e. What Mount did yesterday. That role is more suitable to Jack. Remember that match AstonVilla vs Liverpool. That 7-2 score line. Mount was wasted by Southgate yesterday. Literally one of the worst performance i have seen compared to his best i have ever seen in Chelsea shirt.