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Outside the main five candidates, several big names have been linked with the Celtic job.
Continuing the trend of former players, ex-Celts Paolo Di Canio, Paul Lambert and Roy Keane are considered to be in the running.
Di Canio recently declared his interest in the role, while Lambert remains in the Aston Villa manager's chair despite recent speculation over a departure. Keane, meanwhile, has distanced himself from the job in favour of remaining as assistant to Martin O'Neill with the Republic of Ireland.
Rather surprisingly, O'Neill, who has said he would not stand in Keane's way should an offer come in, is also in the running.
Other previous Celtic managers Tony Mowbray and Gordon Strachan, as well as recently departed assistant Johan Mjallby, have been mentioned by Paddy Power.
It is unlikely any would consider a return, however, with O'Neill and Strachan already having achieved everything possible in Scotland. Both are currently performing well as national team managers of Ireland and Scotland, respectively.
Mjallby, meanwhile, has only just left the club following a four-year spell as assistant to Lennon. As for Mowbray, the disaster of his previous appointment still rankles the majority of Celtic fans.
The biggest names without any tangible connection to the club are ex-Barcelona youth team and Brighton manager Oscar Garcia, Chelsea legend Gianfranco Zola and former Croatia manager Slaven Bilic, who previously declared his interest before Lennon's appointment four years ago.