The Lisbon club where it all began for the 37-year-old could now sign him again on a free transfer - if they can meet his wage demands.
Ronaldo may prefer to remain in the Champions League with Chelsea leading Bayern Munich, Napoli and Paris Saint-Germain in the bookies’ view of the race for his signature. Further down the odds are Arsenal, Newcastle and even Manchester City.
Cristiano Ronaldo next club odds
Sporting CP 3/1
Any MLS Club 6/1
Bayern Munich 17/2
Real Madrid 16/1
Man City 16/1
Atletico Madrid 25/1
Odds provided by Betfair (subject to change)