"You're always coming out trying to impress, you want that shirt come Russia," the 25-year-old told British media.
"It's difficult, you don't know who he's going to pick but that's not up to me to decide," added Walker in reference to manager Roy Hodgson.
"Nathaniel is a great player so whoever gets the nod for the Russia game I'm sure they'll do well. He'll get my full support if he is starting."
Walker says he will handle whatever is thrown his way at his first major international tournament.
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"I don't feel any pressure whatsoever," he explained. "I feel comfortable, I look around and I've got some fantastic players around me.
"I think we can go on and win, there's nothing saying we can't do that ... we had that question all year at Tottenham 'could we handle the pressure?' and I think we did."
Wales and Slovakia are the other teams in Group B.
(Reporting by Ian Rodricks in Bengaluru; Editing by Tony Jimenez)
