Grayson and free agent Nigel Pearson are the two favourites, while Kevin Phillips and German coach Jens Keller from Bundesliga Second Division club Union Berlin also remain high up in the betting.

Sunderland's plans to replace David Moyes in the managerial hotseat have been hampered by ongoing takeover talks, leaving the club in limbo ahead of the players returning from pre-season training on Thursday. Fresh reports suggest Grayson is the leading candidate identified by chief executive Martin Bain but as yet there has been no formal approach from Sunderland.

Grayson is understood to be away on holiday until the weekend with the Preston squad also due back in training at the end of next week. He is reported to be on a one-year rolling contract. Sheffield United boss Chris Wilder had also been linked with the Sunderland job but he is in line for a new deal after leading the Blades back to the Championship.