LONDON — Resting his injured ankle, Cristiano Ronaldo has plenty of time to think about his immediate future.

He could stay with Manchester United, where he is almost certain to get a hostile reaction from the fans who are angry that he has repeatedly said he wants to leave the club. Or he could push ahead with his plan to go to Real Madrid, a dream move, he says, where he will be welcomed by the club's owners, fans and teammates as potentially the world's best footballer.

Simple choice, surely?

Last season, Ronaldo's 42 goals helped United win its second Premier League title in a row and Europe's biggest prize, the Champions League. So he can argue that he's paid his dues at Old Trafford and should have the right to move somewhere else.

United could offer him for sale for what would almost certainly be a world record transfer fee of something like 60 million British pounds (C$119 million). The English champions could use the cash to buy new young talent in the same way it bought Ronaldo as an untried 17-year-old midfielder from Sporting Lisbon six years ago.

Behind what looks like a straightforward piece of football business, however, lurk some murky issues and it could work out badly for Ronaldo, United and Madrid.

Ronaldo has almost four years left on his contract and United is refusing to sell.

The Red Devils are furious that, having stood by him after he returned from the 2006 World Cup a hated figure over his contribution to Wayne Rooney's red card against Portugal, he is about to walk out on them.

During the Portugal-England World Cup quarter-final match, Ronaldo pushed his United teammate in reaction to Rooney's foul on Ricardo Carvalho. He then winked at his own bench after the England striker had been ejected.

Jeered by rival fans wherever United played the following season, he was quickly forgiven by the United supporters who turned him into one of their favourites.

United manager Sir Alex Ferguson also backed Ronaldo. The veteran manager, who has been in charge at Old Trafford since 1986, described the Portugal winger as one of the bravest players he had seen because he would continually run at defenders, get chopped down, and then get up and run at them again. Ferguson moaned that Ronaldo got little protection from referees and was wrongly accused of diving to get free kicks.

But that was before Ronaldo said he wanted to leave.

If Ronaldo moves to Real Madrid, he will be playing for one of United's biggest rivals in the Champions League, and Ferguson's opinion of the player is likely to change. Remember how the United manager fell out with David Beckham after his outside business interests started to overshadow his form for United?

Then there's the thorny issue of loyalty to his contract.

If Ronaldo was happy to sign a five-year deal little more than a year ago, why does he now want to leave? Is it because Madrid is offering him something better, does he want more money from United or may the truth be that winning the Champions League and being lauded as the best player on the planet have gone to his head?

Last week, Ronaldo did himself few favours when he agreed with FIFA president Sepp Blatter that clubs who refused to sell players were guilty of "modern slavery" even though many are happy to sign long term contracts earning them up to 130,000 British pounds (C$257,000) a week.

The critics in the British media turned on Ronaldo, calling him greedy, vain and deluded. So he will have few friends in English football if he stays at United.

Right now he is in Lisbon recovering from surgery to repair his damaged ankle, which is expected to keep him sidelined until October. Ronaldo is in the care of Portuguese national team physiotherapist Antonio Gaspar, and United's medical team are due to assess his recovery in three weeks.

Soon after that, the transfer window closes and Ronaldo may have to stay at Old Trafford until January at least, when it reopens.

If United sticks to its no-sale stance, Ronaldo is obliged to stay and see out his contract, albeit reluctantly.