Neil Lennon enjoyed a fruitful spell as Celtic manager, winning three league titles and two Scottish Cups in four years with the club having taken over from Tony Mowbray in 2010.
The former Northern Ireland international has won two and lost two of his first four games in charge of the Trotters, who were abysmal before his arrival.
With a big job on his hands at the Macron Stadium, this will be the job that defines Lennon as a manager - but he's already admitted that he'd be open to a return to Celtic Park.
Lennon revealed that when he left Glasgow this summer, he had talks with chief executive Peter Lawwell over a possible return in the future, whilst also noted a positive relationship with majority shareholder Dermot Desmond.
"Yeah, I don’t see why not," said Lennon when asked if he would return to Celtic. "I left on very good terms with the Board and with Peter and Mr Desmond. And we did say that if ever the opportunity came up again further down the line, if things were going well for both of us, I would have no hesitation in coming back."
"But I’ve got a lot of work to do myself in terms of my managerial progression before I’d think about that, though. You never say never, but I felt this was a good time to go. I’d had four years of being relatively successful and had some great memories and it’s always good to leave on those terms rather than overstay your welcome."
Current Celtic boss Ronny Deila is already under pressure with the club sitting in third place, but a possible return could be some time off yet.