Real Madrid are reportedly willing to sell the Portugal superstar to Italian giants Juventus for £88million - £2 million more than they paid United to acquire him for a then world-record fee back in 2009.
The Serie A champions are prepared to also pay the 33-year-old more than £500,000 per week and his agent Jorge Mendes is now waiting to see who else might come forward.
However, any dream United fans might hold of welcoming Ronaldo back to the Theatre of Dreams is certainly being downplayed in the corridors of power at the club.
The Manchester giants have twice attempted to re-sign him during the last five years, being rebuffed each time.
Mourinho also had a falling out with his countryman during their final season together at Real back in 2012-13, but sources have since suggested they are back on good terms.
More importantly, United, even with their vast financial resources, might not be able to justify the huge numbers involved, having already spent £75m this summer and being in advanced talks with three other targets.
Ronaldo's commercial star power would certainly offset some of those issues but Mourinho, who shares the same agent, isn't showing any real signs of wanting to get involved at this stage.