Roy Keane and Sir Alex Ferguson haven't always seen eye to eye.

While there's no denying that arguably the Premier League's greatest ever captain and manager enjoyed incredible success together, that didn't always translate to the most cordial of relationships.

In fact, it's no secret that the circumstances under which Keane waved goodbye to Old Trafford in 2005 weren't exactly amicable and it's something that has stuck with the Irishman ever since.

Keane and Ferguson's friction

Keane is well-known for his tough talking and ruthless attitude, so it's no surprise that when the United legend has reflected back on those moments that he hasn't been afraid to speak his mind.

And it often makes for a jarring listen considering that Ferguson is almost universally praised for his coaching style, particularly his man-management that saw him become a father figure to many.

However, it can't be discounted that Keane shared a dressing room with Ferguson more than most players, so his thoughts have often made for both an awkward and fascinating experience.

Jeremy Doku to Liverpool (Football Terrace)

Keane's United exit

And arguably nothing has embodied that fine balance better than when Keane drove the knife into his former boss with a cutting assessment two years ago in Ireland at an event with Off the Ball.

Having spoken openly about his United exit, Keane proceeded to criticise Ferguson for his man-management and the way that Bryan Robson and Steve Bruce were treated when they departed.

However, nothing will have stung more than when Keane decided to combat the idea that Ferguson always had United's best interests because the Irishman pulled approximately zero punches.

ENTER GIVEAWAY

Keane goes in on Ferguson

“People said [Ferguson] always had the best interests of Manchester United at heart," Keane fumed, according to LancsLive. "Darren Ferguson [his son] won a medal. He was very lucky.

"[Alex Ferguson's] brother was the chief scout for Manchester United for a long time. I'm surprised his wife wasn't involved in the staff somewhere.”

"Darren was [the manager] at Preston North End and lost his job," Keane continued. "He had a couple of young players on loan from Manchester United, [but] guess what happens the next day?

"They're pulled out of Preston. Is that doing the best for Manchester United? Do me a favour.”

A severed relationship

Wowsers. Perhaps the only thing more remarkable than Keane openly hanging out his manager to dry is the facial expressions of Gary Neville just a few feet away.

You can tell that there's a part of Neville that wanted to break out into laughter, but his manner seemed understandably consumed by the fact he couldn't really believe what he was hearing.

However, regardless of whether you agree with Keane or not, one can't help feeling a certain sadness that two of the Premier League's greatest ever figures aren't on good terms anymore.

Then again, maybe that's just what you'd expect from two of the firriest individuals that the beautiful game has ever seen.