According to Cadena Cope (h/t Liam Prenderville of the Daily Mirror), the Portuguese's possible switch to Turin is at an advanced stage, so much so that Allegri has been in touch with the forward for discussions.
It's said the pair spoke over the phone about how Ronaldo would fit into the setup at Juventus, as speculation continues to intensify over a potential €100 million (£88 million) switch.
As noted by Prenderville, Ronaldo's possible departure from the Santiago Bernabeu outfit has been discussed since the UEFA Champions League final win over Liverpool, with the striker said to be unhappy with life in the Spanish capital.
As we can see, the Juventus supporters are getting excited about the prospect of Ronaldo donning the iconic black and white jersey:
It's also been reported that current Napoli manager and Ronaldo's former coach at Real Madrid, Carlo Ancelotti, has advised the 33-year-old that a move to Serie A would be to his benefit.
According to Sky Sports (h/t AS), Ronaldo asked Ancelotti for advice on a possible switch to Juventus. The Italian coach is said to have encouraged the former Manchester United man and said "[Allegri] is the perfect coach for you".
While it's difficult to imagine Ronaldo moving given his association with Madrid, the chances of this spectacular transfer coming to fruition appear to be strengthening by the day.
If Juventus were able to pull the deal off it would be an incredible coup, even for a club of their stature. While Ronaldo is 33, he remains in peak physical condition and showed multiple times last season that he is still one of the most effective players in the game.
These numbers sum up just how deadly he has been in front of goal in recent years:
In those five years, Ronaldo has helped Real win the Champions League four times. It also bodes well for the player that when he has come up against Italian opposition in the past he has been able to find the net:
At Juventus a fresh challenge would potentially benefit Ronaldo, as he has won all there is to with Madrid. Allegri has proved himself as a tactician, and it would be intriguing to see what he could draw from one of the all-time great goalscorers.
Still, it's the kind of transfer many will be expecting to unravel up until Ronaldo is pictured in his Juventus shirt.