The Portugal international has been heavily linked with a move away from the Santiago Bernabéu this summer, with French giants Paris Saint-Germain supposedly the frontrunners for his signature.
Stories coming out of Spain last week insisted that Real Madrid wouldn't consider selling Ronaldo and that the reigning European champions have demanded that potential suitors meet his €1bn release clause if they want to start negotiations.
But the Scotish Sun have cited a report from Italian newspaper Libero that insists Ronaldo will return to Old Trafford next season. This continues from claims in his home county that the 33-year-old has already decided to leave the Spanish capital this summer.
Ronaldo first threw his Real Madrid future into question immediately after their Champions League final win over Liverpool.
"Now to enjoy, and in the next few days I will give an answer to the fans that they are on my side," the five-time Ballon d'Or winner claimed last month. "It was very nice to be in Madrid."
Ronaldo has remained coy over his future following those comments but many expect that the Portuguese star will shed further light on the next step in his career after the World Cup.
United fans would likely love the prospect of Ronaldo returning to the club this summer as they look to close the gap on Manchester City, although a potential return could be the catalyst for the end of Anthony Martial's career at Old Trafford.