The Red Devils had Ronaldo on their books between 2003 and 2009, during which time he became regarded as one of the best players in the world, a reputation he has only enhanced further since his move to the Bernabeu.
The Portuguese international has an incredible record of 321 goals in 304 games for Real, and has helped them to glory in La Liga in 2011/12 and in the 2013/14 Champions League.
Still, there is growing speculation that this could be his final season at the club, with the Daily Telegraph reporting in the summer that the player was unhappy with new manager Rafael Benitez and his training methods.
Set to turn 31 in February, Ronaldo has also shown some signs of fatigue this season after a slow start to the campaign, although he has since responded with an incredible eight goals in two games after a long goal drought.
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If Le 10 Sport’s report is correct, it may be that Real will consider selling their star player while they still can, with PSG one of the richest clubs in the world and likely to be willing to offer big money for the 30-year-old.
Another report from the Telegraph in the summer linked PSG with an £87m move for Ronaldo, and that would be money that Real would have to consider accepting for a player possibly heading into the final few years of his career.