The warning signs were evident even before Ferguson joined Rangers in a British-record transfer from Dundee United.
Having signed as a schoolboy, he won the Scottish Youth Cup with the Tannadice club and was only 18 when Jim McLean brought him off the bench for his debut in a 2-1 win against Rangers at Ibrox in 1990. His potential was obvious, but the fledgling striker butted heads with iconic chairman and manager McLean on more than one occasion. Ferguson was fined so frequently he complained he "was always skint, I had nothing."
Amid a smattering of appearances that season, the towering forward scored the winner against St Johnstone to send United to the Scottish Cup final, where they lost to Motherwell. The next season, Ferguson cemented his place in the starting XI.
"He was an honest, naive and immature big lad," team-mate Maurice Malpas told The Courier. "On the park he was someone you wanted on your team. He was quick, he wanted to turn and he wanted to run. He did some stupid stuff, but he was immature and just never really matured."
At 18, Ferguson broke his toe when he kicked a toilet door in anger following a fight over a woman in a Dundee pub. The other party, significantly shorter than Ferguson, said that he gave him a Glasgow kiss before the footballer could get up off his stool, explaining to The Courier: "I stuck the nut on him... I wasn’t going to wait until he stood to his full height."
In February 1991, Ferguson received his first conviction, being hit with a £100 fine for headbutting a police officer in Stirling, plus a further £25 for breach of the peace. By the time his second conviction came around - a £200 fine for punching and kicking a 19-year-old postman who was on crutches in a Stirling taxi queue - he was already making a name for himself as a prolific scorer in the top-flight.
"I can't remember him on a crutch. He swung at me a wee bit. I was daft," Ferguson told BBC Sport of the latter incident. In court, the victim denied claims that he had provoked a response from Ferguson, but admitted that he might have called the footballer's girlfriend "a trollop".
When police arrived at the taxi rank and found Ferguson standing over the injured postman, kicking and punching him, he told them, "I done it, but he was mouthing off." He said in court: "I punched him in the face because I thought he was going to hit my girlfriend, and in turn, myself. I hit him and we both fell and after I got up, I booted him in the rib cage."
Asked why he didn't walk away when the man was lying on the ground, he said: "I kicked him to keep him down. I have never walked away in my life." With the benefit of hindsight, would he act differently? "I would do the same again," he said.
Just a few months after that ruling, Ferguson was convicted for a third time. In November 1992, after a Player-of-the-Year awards ceremony, he entered a hotel bar in the quiet fishing village of Anstruther wearing, according to bar staff’s court testimony, a women’s silk glove, a clip-on earring and a flower behind his ear.
According to reports, Ferguson was buying a round of drinks when a fisherman at the bar started winding him up, eventually saying: "I’ll f*cking give you..." But before he could utter the word "trouble", Ferguson was on him, later recalling: "As he made to get up from his stool, I sensed what was coming and didn't wait. Boom. The fella slid off his stool and all hell broke loose. It was like the Wild West."
It was said in court that Ferguson, then 20, continued to punch the 29-year-old on the head before two men threw the striker out of the pub. When the police came looking for him at 4am, Ferguson was "Laid out on the sofa, rotten, stinking drunk." He was naked apart from "a pink hat someone had given me earlier…I had lipstick on, an earring and a silk glove. And nothing else."
He added: "The police took one look at me and said: ‘We’ll come back later.’ Which they did."
There was a real danger of Ferguson going to prison for that altercation, but he got off with a year’s probation. However, his off-field behaviour infuriated legendary Dundee United chief McLean, and the club publicly confirmed that he had been dropped from the squad.
"I was getting fined for daft things," Ferguson recalled on The Overlap. "I’d take the manager’s car as he’d told me to wash it, so I used to take it and drive it into a car wash, and next thing you know there are four or five of us in the car driving around Dundee. The police would stop us, it was nuts. That's what we did."
The situation grew so dire that after a match against Motherwell was postponed, the club publicly announced that Ferguson would not have been involved even if it had gone ahead.
"Other problems relating to breaches of club rules, and his refusal to accept the club's disciplinary code, which applies to the entire playing staff, are major factors [in his absence]," the statement read. "Until he provides Dundee United with a guarantee that he will adhere to these rules, he will not be considered for first-team duty. The club believes that press speculation as to Duncan Ferguson's future has not helped the situation. Regarding such speculation, the club repeats that Duncan Ferguson is not for sale."
Leeds United tabled a £1 million offer which Chelsea reportedly matched despite United’s assertion that he would not be sold. In the end, Rangers came forward with a British-record £4m offer, and the Tangerines accepted.