The England international came on as a substitute when Sullivan was dismissed for hauling down Paul Evans during the goalless draw in the Worthington Cup on Tuesday evening.
And, with the Scot facing a likely one-match suspension for denying the Bees midfielder a goalscoring opportunity, Walker will be given another opportunity to show he should be Graham`s first choice.
However, it is now certain that the son of former Norwich manager Mike will be in the shop window, rather than playing for his place, following his transfer request and comments claiming that Graham has treated him like "crap".
The 28-year-old feels he should still be between the posts at White Hart Lane but Spurs` decision to accept his desire to move on means that the transfer listed keeper will be plying his trade elsewhere when a satisfactory bid is forthcoming.
Meanwhile, Graham was displeased with Sullivan`s dismissal, slamming: "I`ve seen the incident on the video and there is no way it is a sending off.
"At the time, I thought it was but, now I`ve seen it again, the goalkeeper hasn`t touched him.
"Sullivan has come out, the boy`s got there first, jumped over him and then gone down.
"I couldn`t have said that until I saw the video. Maybe that`s why the referee thought it was a sending off."
