How much longer can Cristiano Ronaldo stay at the very top? 

That will have been the question echoing around the Juventus boardroom when the Old Lady hierarchy sanctioned his €112million transfer from Real Madrid in 2018. 

Now, there are two different names on their radar: Kylian Mbappe and Erling Haaland. 

It would be naive to say Ronaldo shows no signs of slowing down despite his record 16th consecutive Ballon d'Or nomination. 

Even in his final years at Real Madrid, the Portuguese changed his game as he came to terms with losing some of his pace. 

On the one hand, that is part of what makes him so remarkable.

His adaptability and his drive to remain among the greats is what sets him apart - some would even say it separates him from Lionel Messi, even if that is increasingly becoming a minority view. 

Bianconeri boss Maurizio Sarri told reporters on Friday that he is considering resting Ronaldo soon. 

"Even he will have to take a break, but I don't know when," he said. 

"I speak to him every day, about how he feels on the pitch and the numbers that come from the doctors and fitness coaches at the end of the match. We will make the decision based on how he feels."

The Serie A champions are prudent to have one eye on the future. 

From a 34-year-old considered one of the greatest of all time, to a 20-year-old who is already dominating all before him in Europe, it is no surprise that Mbappe is viewed as a potential heir, as reported in Tuttosport. 

Real Madrid have long been monitoring Mbappe, which means his price tag could be elevated to a world record €300m, surpassing current teammate Neymar. 

The Paris Saint-Germain striker has scored 66 goals and assisted another 36 in 95 appearances since moving to the French capital from Monaco. 

This season alone, the World Cup winner has already scored six goals and four assists - meaning he has created a goal every 44 minutes.

Last week, he broke another record by scoring the quickest hat-trick by a substitute in Champions League history, taking just 22 minutes to score three times against Club Brugge. 

The alternative Juventus have in mind, Haaland, has also been impressing in Europe. 

The Red Bull Salzburg and Norway striker has scored 20 goals already this season. 

Towards the end of the 2019/20 campaign, the teenager began to make headlines across the world when he scored a triple hat-trick - that's right, NINE goals in a single game - against Honduras U20. 

Whoever bags either of their signatures in the coming years will have a lofty bill on their hands and rightly so.