Bernie Ecclestone and Gerhard Gribkowsky clashed over "control" of formula one.
That was the testimony on Wednesday offered in court by investigative author Tom Bower, who in 2011 wrote a biography about the embattled F1 chief executive called "No Angel -- the secret life of Bernie Ecclestone".
Bower gave the book its title when Ecclestone, who worked closely with the author at the time, reportedly told him: "Write what you like, provided it's more or less the truth."
Bower was called to give evidence in the Munich trial on Wednesday, as Ecclestone fights for his future in formula one, and for his very freedom, over allegations he bribed jailed F1 banker Gribkowsky.
Bower also knew Gribkowsky well, and told the court how the jailed former BayernLB risk officer once told Ecclestone he was going to try to find a successor for the 83-year-old Briton.
"We will see what happens if you carry on like that," Bower quoted Ecclestone as having replied to Gribkowsky, who interpreted the retort as a threat.
German media reports quote Bower as also telling the court on Wednesday that Ecclestone and Gribkowsky waged "a battle for control of formula one".