Grealish, who joined Everton on loan from Manchester City on Tuesday, explained his decision to wear the No18 in an interview with the club's media team. He said that there was a special reason behind his choice, aside from other available numbers.
He mentioned that both Gascoigne and Rooney, two of his favorite English players, had worn the No18 shirt during their time at Everton. Grealish was keen to follow in their footsteps and chose the number as soon as he knew he was close to joining the club.
Before arriving at Everton, Grealish had a conversation with Rooney about his choice of shirt number. He hoped that Rooney would be happy with his decision, and we can be sure that he is.