Celtic boss Martin O'Neill has previously revealed one of his worst transfer mistakes as a manager.
O'Neill, 73, made a shock return to Celtic in October 2025 after the resignation of Brendan Rodgers.
Despite positive results, O'Neill departed on December 3 and was replaced by Frenchman Wilfried Nancy.
However, Nancy's tenure lasted just 33 days as he was sacked after losing six out of eight matches in charge.
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Following Nancy's dismissal, it was confirmed that O'Neill would make another return and take charge until the end of the 25/26 season.
Since then, the 73-year-old has led Celtic to five wins and two draws as they look to overhaul Hearts in the race to become Scottish Premiership champions.
Back in 2000, O'Neill took charge of Celtic for the first time.
His tenure lasted nearly five years as he managed 282 matches, with a record of 213 victories, 29 draws and 40 defeats, which equated to a win rate of 75.5 per cent.
Speaking back in October 2025, O'Neill was asked to name his worst signing as Celtic boss.
The Irishman named Middlesbrough legend Juninho Paulista, who scored 29 goals and assisted 18 in 125 Premier League appearances, as one of his biggest transfer mistakes.
O'Neill said to Record Sport: "In terms of worst signings, actually funnily enough, I actually signed a Brazilian player, Juninho, who had been wonderful for Middlesbrough, really terrific footballer for Middlesbrough.
"In fact, I had to man-mark him in the 1997 League Cup final for Middlesbrough versus Leicester because he had destroyed us a couple of weeks earlier in a league game at Filbert Street.
"So he was a really good player. But by the time that I’d signed him, he had been at Middlesbrough, I think three times, you know, back and forward. So he had lost the edge. He was no longer the player he was."
He continued: "And I suppose maybe I thought that for periods we could actually rejuvenate him, but it never really materialised.
"But we didn’t pay any money for him at the end of the day. He came on a free transfer. And in truth, I think that his great days had certainly passed by that time."
In total, Juninho made 22 appearances for Celtic, scoring only once. He eventually left for Palmeiras in 2005.
Marcus Chan