Rio Ferdinand has revealed that he and former Manchester United team-mate Wayne Rooney would engage in foul-mouthed clashes in 'every training session' during their time together at Old Trafford.
The duo won a host of trophies and accolades during the eight years they spent together at United and also often played together for England.
Ferdinand was an integral part of the time that won three consecutive Premier League titles, while Rooney is the club's all-time leading goalscorer.
Although they may be friends to this day off of the pitch, Ferdinand has lifted the lid on their fiery clashes on the training ground - with the 43-year-old admitting that Rooney was "unplayable" when he was angry.
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"Angry Wayne Rooney is playing in my all-time Premier League XI," Ferdinand told Vibe with Five.
"I used to have him on a bit of string. Oh my god, we used to argue every training session. Me and him used to swear at each other and argue like you'd never know - in games and training.
"Just that anger, whether same team or opposite team it didn't matter, I'd be shouting at him about something, he'd be shouting at me about something, just growling.
"The Rooney that played as a No 9, I think he was almost unplayable at times,' Ferdinand added.
"As a nine he was a joke, even in the Euros when he first dropped onto the scenes. He was doing mad stuff, like, "Wow, who is this?".
"He was just like a machine. That's the only thing I would think of, if a player was a bit of a needle I'd try and get into it and wind him up.
"That's what I would have done, try to wind him up maybe. And you're hoping he maybe leaves it late on someone and gets a red card."
Since hanging up their boots, Ferdinand has moved into punditry whereas Rooney is currently cutting his managerial teeth in the Championship at crisis club Derby County.
The former United star is winning a host of plaudits for his work keeping the Rams' unlikely survival hopes alive against the odds, with Ferdinand admitting earlier this month that Rooney had impressed him.
Ferdinand previously said: “I've seen a different Wayne Rooney to the one I grew up with and saw grow up at Man United, it was a real positive experience. It was the confidence and I didn’t expect it from such a young coach.
“I thought there’d be a lot of, ‘ermmmm’ – you see the interviews, no disrespect – but he was just calm man, I was so impressed. The results he is getting off the back of it, I’m not surprised.
“Wazza is good at detail, his game was about detail. People would think it was hustle and bustle and bang, a shot out of nowhere but to be the player he was you had to understand details and it is about translating that into the team."