Xavier senses the changes taking place in Jean Grey, and returns to Earth to help and resume leadership of the X-Men. Shortly thereafter he battles his pupil after she becomes Dark Phoenix and destroys a populated planet in the Shi'ar Empire. It hurts Xavier to be on the opposite side of Lilandra, but he has no other choice but to challenge the Shi'ar Imperial Guard to a duel over the fate of the Phoenix. Xavier would have lost against the greater power of the Dark Phoenix, but thanks to the help Jean Grey gives him (fighting her Phoenix persona), Xavier emerges victorious; she later commits suicide in order to prevent herself from endangering more innocent lives.