Ryan Garcia hit out at former trainer Joe Goossen after the former moved to oversee Mario Barrios at a lively press event on Thursday.
The pair will meet for the latter's WBC welterweight title at the T-Mobile Arena in Las Vegas on February 21, live on DAZN PPV.
The bout marks a reunion for Garcia, now trained once more by his father Henry, with the main who formerly guided his career.
Amid a media conference where the star played up to hyper-antics however, he took time to air his frustations once again to him.
"It's insane," he said, cutting across his former trainer. "You broke my heart. It's over. We're done. I'm breaking up with you again.
Goossen replied that he believed his actions towards Garcia had been "courteous", adding: "I hope you don't take offence to it."
Later, the fighter dug into a backpack he had brought to the conference and presented his former trainer with a black slogan t-shirt.
Daubed with the words I'M A TRAITOR, the star doubled down, making reference to the television series The Traitors in his address.
Later, Garcia did give credit to Goossen, along with his other team members, adding: "I'm grateful for all the experiences I've had.
"I've had a lot of great memories with them. They taught me a lot of stuff. Hopefully, that knowledge soaked in. We're ready to take over."
Few bouts involving Ryan Garcia tend to need any extra narratives spun into the wider web constructed around the hard-hitting star.
But the presence of Joe Goossen in the opposite corner behind Mario Barrios has certainly brought some added spice to this clash.
Garcia and father Henry both aired their frustration with their onetime colleague on stage, with the former interrupting his own remarks.
For Barrios, the bonus of having that first-hand knowledge will be something he will not wish to overstate when it comes to an advantage.
Yet it undoubtedly adds a new page to a book that seems to swell with every new chapter in the life of an American boxing favourite.
Subscribe to DAZN's new Ultimate Tier to get a minimum of 12 PPV events included per year, including Lopez vs. Stevenson, and Barrois vs Garcia, on top of another 185 fight nights. Plus Serie A football, watch on multiple devices, and many more extra benefits.
Sign up for £22.99 in the UK / $44.99 in the U.S. More details here.