Tour de France 2012 champion Bradley Wiggins almost withdrew from the race in a row over team-mate Chris Froome, former Team Sky general manager Sean Yates said in extracts from his new book published on Thursday.
Wiggins was Sky's team leader during the race but Yates claims that an unplanned attack from Froome during stage 11 in the Alps made him threaten to pull out.
In an extract from his book serialised in The Times newspaper, Yates says Wiggins responded to the incident by sending him a text message that read: "I think it would be better for everyone if I went home."
Yates added: "He (Wiggins) was upset and felt like Froomey had stabbed him in the back after the discussion we'd had before the stage (when Froome had agreed only to attack in the last 500 metres).
"He couldn't understand why he'd gone back on the agreement, especially when everything was going so well.
"There were only four kilometres left at that point and Brad went on to win by three minutes, so the maths say that he would still have been comfortably on top in Paris.
"However, his mental state was always fragile, and that psychological blow could have been a knockout one."
Wiggins's victory made him Britain's first ever Tour de France champion. He was succeeded by compatriot Froome this year after injury and illness prevented him from defending his title.