Roy Keane didn't exactly mellow his character when he released his 2014 autobiography 'The Second Half', revealing remarkable stories and taking fire at a series of big names.

Whether as a player, coach or pundit, Keane is notorious for his brutal quips and frosty honesty. It's often the source of great controversy and debate but, let's be honest here, nobody would have him any other way.

Besides, who other than Keane to take on the likes of Peter Schmeichel and Sir Alex Ferguson in their book? Even four years on, it makes for remarkable reading.

Nobody was free from the Irishman and, as a result, there was a special mention for none other than Cristiano Ronaldo.

Joining Manchester United in 2003, the five-time Ballon d'Or winner only spent a brief spell at Old Trafford with Keane as his skipper but made quite the impression in that short time.

In fact, while Keane spent paragraphs sinking his teeth into arguably the greatest manager of all time, a contender for the greatest player of all time was able to touch his more complimentary side.

Should we be surprised? Although Ronaldo arrived in England as a skinnier and less mature version of his current self, the undercurrents of greatness were certainly apparent.

Just take Keane's legendary passage of the Sporting Lisbon debut that propelled CR7 to stardom, writing: "Sheasy ended up seeing the doctor at half time because he was actually having dizzy spells. The club concluded negotiations after the game.

"We always joked with Sheasy he had actually sealed the deal by playing like a f****** clown."

Eloquently put, Roy, and United did indeed sign Ronaldo quickly after. That's all well and good, though, but how did Ronaldo actually take to life at Carrington?

Keane had that covered, too, in another brilliantly phrased and honest section.

The Irishman penned: "I liked Ronaldo straight away. He had a nice presence about him and a good attitude.

"After watching him train for a few days I thought: 'This lad is going to be one of the best players in the world.'

"He was seventeen, but he was immediately one of the hardest working players at United.

"He was good looking and he knew it. Looking at some of the other players in front of the mirror I would think: ‘You f------ nugget’. But Ronaldo had an innocence to him and a niceness."

When you consider the dizzying heights Ronaldo's career has reached since, there's a certain magic to hearing about his first steps in the big time.

And if you can make a first impression like that with Keane, you're halfway there.

Do you think Cristiano Ronaldo is the certified GOAT? Have your say in the comments section below.