Cristiano Ronaldo is one of the greatest footballers - and strikers - of all time.

Having scored over 800 goals throughout his mammoth career and winning just about everything there is to win along the way, it's hard to dispute his status as arguably the greatest player ever.

He is without doubt in the conversation. And what makes his body of work even more remarkable is seeing his career path, where he transitioned from a tricky winger into the most lethal number nine imaginable.

Ronaldo is a bona fide penalty box poacher. Get the ball in and around him within that 18-yard box and he will more than likely find a way to get it into the back of the net.

His abilities in front of goal are frightening, and stuff you'd genuinely think was unteachable at times. From his detailed, intricate movements to create space, to his freakish heading ability, positioning and unrelenting shot power, he really has everything you'd want in a striker if you were able to design one from scratch.

So to know that all of those qualities were once that Ronaldo did consciously go and learn is incredible. And not only did he learn such a difficult craft - he mastered it.

Ronaldo was always electric as a left winger in his younger days and absolutely was at elite levels, but it was him morphing into a forward that has cemented his legacy. We saw ever so slight glimpses of it during his first spell at United, but it was while at Real Madrid where he began to transition properly.

CHELSEA SIGN WESLEY FOFANA (Football Terrace)

A fascinating insight into where it properly began for Ronaldo as a central striker has gone viral on Twitter, with @Luukinho9 posting footage of Jose Mourinho discussing the transition and it gaining over 4,500 retweets and almost 30,000 'likes' at the time of writing.

Mourinho explains his decision to leave out Real Madrid's three typical strikers against Barcelona in the 2011 Copa Del Rey final, in order to play Ronaldo in the role. Check it out below.

WATCH: Mourinho explains decision to play Ronaldo at striker

What a brilliant insight and analysis from one of football's greatest managers, discussing one of football's greatest players. Let's see what he had to say.

"Sometimes you have to move the pieces of the chess, to try to create the best solution for the team."

Mourinho explained how he first deployed Ronaldo as a number nine in the final against Barcelona, opting to do so because he didn't want him spending the game doing more defending than attacking by keeping tabs on Dani Alves at right-back.

Real Madrid's 2011 Copa Del Rey winners

MADRID, SPAIN - JANUARY 20: Cristiano Ronaldo (L) of Real Madrid celebrates with teamates after scoring Real's first goal during the Copa del Rey quarter final second leg match between Atletico Madrid and Real Madrid at Vicente Calderon Stadium on January 20, 2011 in Madrid, Spain. (Photo by Denis Doyle/Getty Images)

"We had three number nines. And for the final, I left them, all three, out, to play Cristiano as a number nine."

He added shortly after: "If Ronaldo played against him [Dani Alves], he would be chasing him all the time. Playing more defensive than offensive.

"So I decided, 'No, you are not going to chase anyone. You are going to play number nine, you are to play central. You are going just to try to score goals'."

And score he did. Ronaldo played the role to perfection, fashioning chance after chance at centre-forward and scoring the all-important, cup winning goal with his head, as Real lifted the Copa Del Rey in a 1-0 victory thanks to him.

"He scored the winning goal. Incredible header. And we won the cup."

Ronaldo scores the winner in 2011

VALENCIA, SPAIN - APRIL 20: Cristiano Ronaldo of Real Madrid (R) scores the winning goal during the Copa del Rey Final between Real Madrid and Barcelona at Estadio Mestalla on April 20, 2011 in Valencia, Spain. Real Madrid won 1-0. (Photo by David Ramos/Getty Images)

Need he say anything more than that? It was a stroke of genius from Mourinho, who clearly recognised that Ronaldo was so good that he could provide a goal threat from anywhere.

We were all aware of Ronaldo's abilities at this point, but nobody thought we'd see the tricky winger turn into a veteran penalty box killer like he has done. It's testament to Mourinho's vision, and Ronaldo's tireless work rate and understanding of the game.

From that point, Ronaldo morphed into a more central figure despite the presence of Karim Benzema, rotating with the Frenchman and staking his claim as the most lethal forward in world football, firing his way to countless honours, records and titles.

Seeing the way he operates now compared to what he started out like all those years ago is incredible and prove just how legendary he is.

The ultimate Cristiano Ronaldo quiz