Duncan, then considered a rising star at Liverpool, made headlines in 2019 when then-agent Saif Rubie accused the club of causing the youngster "deep mental health issues" before negotiating a move to the Serie A team. The Reds always denied such claims.
However, the attacker – who is also a cousin of Reds legend Steven Gerrard – has struggled since the transfer and now plays for Spanish third-tier team Real Balompedica Linense after a failed spell at Derby County.
On Monday, Rubie made an explosive radio appearance, telling talkSPORT: "I actually advised him [Duncan] to stay at Liverpool and you have to understand one thing, which is what I was trying to tell you guys, my job is to do the best for whoever is telling me to help them.
"In that particular case, you can choose to believe me or not, I thought him staying was the best outcome. It wasn't meant to be, and in the end it got a bit ugly with Liverpool, which is unfortunate."
But Duncan, who dropped Rubie as his agent shortly after joining the Viola, has refuted those claims in a series of fiery tweets, asserting: "You and I both know the truth.
"I didn't have a decision nor say as you took it upon yourself to jeopardise my career and to turn a local lad away from his boyhood club and leave me and my family to pick up all the pieces.
"Not once have I spoken upon this topic in four years as it's been my main priority to get my career back on track. Yet you think you have the right to mention my name on a live radio show.
"The truth will be told by myself when the time is right. I should never have trusted my career in your hands. I have learnt my harsh lesson there. And I just pray you have learnt yours as it could ruin another young boy's career.
"And lastly, just to clarify, there was no advising given as you point blank made your mind up, publicly, and by then the damage had been done."
Rubie also worked as an intermediary on Antonio Rudiger's move from Chelsea to Real Madrid earlier this year and used his radio appearance to claim Los Blancos' offer was the smallest the German received.
"Antonio Rudiger has been one of the best, if not the best, defender in the world and Premier League," he said.
"It made Carlo Ancelotti want to bring him to Real Madrid. What is the value of a top-flight, top-level centre-half in the game?
"What if I told you Chelsea, and the old regime, basically made next to no effort to keep the player.
"At the time he was very happy to stay and potentially be the captain of the club. He was offered a contract that was half the amount Romelu Lukaku was earning.
"Let me confirm this, live on air, the Real Madrid deal was the smallest deal on offer. There was a club in England offering almost double the amount and a club in Europe doubling the amount.
"I'm not going to discuss the specifics. Everyone knows there were teams interested in this player. He was one of the best in the world."
From their five Premier Leagues and two Champions Leagues, plus last month's Club World Cup triumph, the Blues have won it all under the Russian billionaire.
But amid mounting political pressure following Russia's invasion of Ukraine, Abramovich is reportedly open to selling Chelsea for the first time.
TOP STORY – THREE PARTIES INTERESTED IN BLUES
According to The Telegraph, at least three parties are circling Chelsea in the belief that Abramovich is ready to walk away.
Abramovich announced on Saturday, a day before the Blues' EFL Cup final loss to Liverpool, that he is taking a step back from his duties as owner.
The report indicates that Chelsea are bracing themselves for bids as early as this week as a changing of the guard at Stamford Bridge becomes a realistic possibility.
ROUND-UP
- Manchester City have ramped up their interest in Borussia Dortmund's in-demand striker Erling Haaland, according to The Express. City chief Txiki Begiristain is said to have recently met with agent Mino Raiola to discuss the signing of Haaland.
- Ralf Rangnick has been ruled out of the running to become Manchester United's next permanent boss. The Sun claims that Mauricio Pochettino and Erik ten Hag, in charge of Paris Saint-Germainand Ajax respectively, are the two men being considered.
- Sky Sports News reports that Antonio Rudiger's representatives remain in constant dialogue with Real Madridand PSG over an end-of-season transfer. Chelsea want to keep hold of the defender, but they have been unable to agree fresh terms.
- According to football.london, Arsenal are eager to reward Bukayo Saka with a new deal at the end of the campaign. The England international is already under contract at Emirates Stadium until July 2024.
- Atletico Madrid midfielder Hector Herrera will see out the remainder of the 2021-22 LaLiga campaign before making the switch to Houston Dynamo in MLS, Fabrizio Romano suggests. Herrera has made 14 appearances this term and is a regular for Mexico.
The Portuguese only took over in June but his side are eighth in the Premier League with five losses already.
Spurs were humbled 3-0 at home by under-pressure Manchester United on Saturday.
Supporters made their feelings known at full-time as boos rung out around Tottenham Hotspur Stadium.
TOP STORY – SPURS READY TO REPLACE NUNO
Tuttomercato claims that Tottenham are working on a deal to have ex-Inter boss Antonio Conte replace Nuno Espirito Santo as manager.
Football Insider also reports that Spurs will sack Nuno this week, with Ryan Mason to be installed as their interim boss again.
The Standard claims that Porto head coach Sergio Conceicao is also under consideration for the job.
ROUND-UP
- Le Parisien reports that Paris Saint-Germain could sensationally walk away from their contract with off-season signing Sergio Ramos, who is yet to debut for the club due to ongoing injury issues from his time at Real Madrid. PSG are said to believe they were misled about his injury status.
- Barcelona are interested in a loan deal for Manchester United's wantaway Dutch midfielder Donny van de Beek, reports Sport.
- Real Madrid are considering moves for Manchester United's Paul Pogba and Chelsea's Antonio Rudiger, claims Marca.
- Theo Hernandez will ignore Manchester City 's advances and pen a new deal with Milan, reports Calciomercato.
- Tuttosport reports hot property Fiorentina forward Dusan Vlahovic wants to join Juventus amid interest from Tottenham, among others.
