Postecoglou's most recent stint was at Nottingham Forest, where he had a short and challenging tenure as a permanent manager. Despite having a first-team squad behind him, he was unable to achieve positive results, with only two draws and six losses in eight games. However, his reputation as a good manager remains intact.

Other potential candidates for the Celtic job include Robbie Keane, a former Celtic player and current Ferencvaros manager, and Kieran McKenna, the manager of Ipswich Town. Keane has knowledge of the club and its culture, but his managerial experience is limited to the Hungarian league, Israeli Premier League, and Indian Super League. McKenna, on the other hand, has had success with Ipswich Town, leading them to promotion to the Premier League and achieving a win percentage of at least 50% in the Championship.

While Postecoglou may be the most suitable candidate at this point, the club will consider other options if he declines the offer or prefers to take a break from football management. The decision will be crucial in determining the team's future success.