Birmingham caretaker manager Eric Black has quit the midlands club and intends to link up with Steve Bruce at Wigan.
Black ended his association with Blues earlier on Tuesday after a brief spell in charge as caretaker boss.
The way now appears clear for Birmingham to step up their plans to bring in Scotland manager Alex McLeish as Bruce's replacement.
Black was understood last week to be a strong contender to become Bruce's successor when the former Blues boss left for Wigan earlier this month, and he was in charge for Saturday's home game with Portsmouth.
But a meeting with the Birmingham board after the 2-0 defeat left Black with no assurances over his future and now he has decided to call time on his two-and-a-half-year reign at St Andrews.
Black has built up a close bond with Bruce after becoming his number two in succession to Mark Bowen, who has since joined Blackburn.
It is understood that City are confident of being given permission by the Scottish Football Association to speak to McLeish despite initial public statements to the contrary.
McLeish would cost City around £1million in compensation but that would not be a problem as they received £3million from Wigan as compensation for Bruce's departure.
The club confirmed Black's departure in a statement: 'Birmingham City Football Club can confirm that Erick Black has been released by the club to join Wigan Athletic.
'Black will link up with former Blues boss Steve Bruce at the Latics.
'He had been at St Andrews since July 2004 and leaves with the best wishes of everyone at the club.'