Veteran manager O'Neill returns to Celtic as Nancy sacked after eight games
Martin O'Neill is back in charge at Celtic until the season concludes after the Scottish title holders dismissed Wilfried Nancy following six losses in only eight matches under the French coach.
In comparison, the 73-year-old O'Neill secured seven victories out of eight when he served as temporary manager for eight games after Brendan Rodgers departed in October.
O'Neill, who managed the Glasgow club full time from 2000 to 2005, made way for Nancy in early December.
However, Nancy lost his job on Monday after managing just eight games, which included six defeats.
"I am truly delighted, actually very privileged to be invited back to lead the team once more, and I look forward to resuming work with the players," O'Neill stated on Celtic's official site.
"We all would have preferred a different outcome under Wilfried, and I personally wish him the best in his future endeavours in football. He is an excellent individual, and I am confident he will succeed again.
"I have been requested to undertake this important role once more, and my priority will be to restore our winning form if possible. We require full support from everyone."
O'Neill resumes with Celtic holding second place in the standings, trailing leaders Hearts by six points, after a 3-1 home defeat to rivals Rangers.
The loss in the Glasgow derby prompted demonstrations by discontented supporters outside Celtic Park and indicated that Nancy's tenure at the club was approaching its conclusion.
A club announcement released earlier on Monday verified the termination of the 48-year-old's short stint.
"Celtic Football Club today confirms that it has chosen to end the contract of manager Wilfried Nancy with immediate effect," the statement read.
The Hoops also noted that the Frenchman's coaching team and Paul Tisdale, head of football operations, have departed the club.
Celtic's interim chairman Brian Wilson described the outcome for Nancy as "a profound letdown, especially from a compassionate viewpoint".
Yet he emphasised that O'Neill's comeback allows Celtic to "anticipate positively," highlighting the ex-Republic of Ireland manager as "a figure familiar to players, staff, and fans, boasting an unmatched standing in football and strong loyalty to Celtic".
'Kamikaze' Nancy
Nancy, who formerly led MLS team Columbus Crew, began his role as Celtic manager on December 4 with a two-and-a-half-year deal, succeeding interim manager O'Neill.
Yet the hiring soon deteriorated, featuring four losses in his initial four outings, such as a 3-1 defeat to St Mirren in the Scottish League Cup final.
Nancy achieved his debut wins in late December, as Celtic triumphed over Aberdeen and subsequently Livingston.
But they fell to Motherwell and faltered at home against Rangers, even though they led at Celtic Park.
Ex-Celtic forward Chris Sutton likened Nancy's situation to that of Ruben Amorim, dismissed as manager of faltering English powerhouse Manchester United mere hours prior on Monday, "though in a briefer timeframe".
"He obsessed over altering Celtic's approach, shifting to a 3-4-3 formation and sticking to a specific style," Sutton remarked to Sky Sports News. "He lacked flexibility, and for Celtic to suffer six losses while conceding so many goals, it was reckless from Nancy."
Celtic and Rangers constitute Scotland's "Old Firm", each having claimed the Scottish title 55 times.
Celtic, the inaugural British side to claim the European Cup in 1967, has captured 13 of the last 14 league championships.
O'Neill's initial match back will occur in a Scottish Premiership home encounter versus Dundee United on Saturday.