Cristiano Ronaldo's footballing career could have ended before it had even began were it not for a heart operation when he was just 15 years old.

According to the Sun, doctors diagnosed a 'racing heart' when Ronaldo was in his mid-teens and it was feared the Portuguese winger, now the World Footballer of trhe Year, would have to give up playing.

He was playing for Portuguese side Sporting Lisbon when the problem emerged.

He underwent thorough medical examinations and it was decided to operate to solve his irregular heartbeat.

The condition is not uncommon and many high-profile footballers have suffered from heart difficulties.

Former Manchester City midfielder Marc-Vivien Foe died while playing for Cameroon in 2003, while France World Cup winner Lilian Thuram was forced to retire last year because of a heart problem.

Portsmouth striker Kanu is another with a history of heart concerns. However, fortunately for Ronaldo, delicate laser surgery cured his problem and enabled him to become the world's No 1 player.

Ronaldo's mother, Dolores Aveiro, said: "His heart raced a lot when he wasn't running.

"The people in charge at Sporting alerted me and I went to Portugal where I had to sign some papers and authorise him being treated in hospital.

"They used a sort of laser to cauterise the source of the problem. He was operated on in the morning and came out at the end of the afternoon.

"Before we knew exactly what he had I was worried because there was the possibility of him giving up playing football.

"But the treatment went well and after some days he was back at training again."

MANCHESTER United's injury crisis is starting to ease - an ominous sign for their Premier League title rivals.

The Reds have risen to the top of the table despite a crowded treatment room and received a further boost on Wednesday night when Liverpool were held to a draw by Wigan.

Rio Ferdinand, Wes Brown and Ji-sung Park made their return from spells on the sidelines against the Baggies, and Patrice Evra (ankle) and Nani (groin) are set to return for the home clash with Everton on Saturday..

"Things are looking up and players are starting to come back," said Sir Alex Ferguson. "Patrice may have a chance for Saturday against Everton. If the game had still been on Monday I'd say he'll definitely play. But he's still got a chance of making it.

"Nani should also be fit for Saturday as well. The ones still unavailable are Jonny Evans, Rafael and Fabio, and Anderson."

But Fergie added that Wayne Rooney wouldn't be rushed back.

"Wayne has never had a hamstring injury before and there's no way we will bring him back early," he said. "He's doing terrific work in the gym and, in terms of his rehabilitation, is on the mend."

Ferdinand, meanwhile, has warned United's rivals that the Reds have got their business head on.

With five goals at the Hawthorns against West Brom on Tuesday, and a new Premier League defensive record to boot, the champions have signalled their intent.

The England defender returned against Albion after missing nine matches with a back problem and he's watched his fellow world champions develop a cold-eyed focus.

"We have got players who are very businesslike at the moment, wanting to get the job done, score goals, wanting to defend, and defend for our lives, and keep clean sheets," he said.

"With that form, you are on to a good thing. But medals haven't been handed out yet so we are not going to get ahead of ourselves.

"We got to where we wanted to be after Japan and now it is all about continuing what we have been doing.

"We have just got to the top of the league and we need to consolidate on that now, try to keep the momentum and get more points on the board.

"If we continue to do that, in the manner we have done in the last few games, we have got a great chance of picking up some silverware.

"We didn't win the league for a few years until we won it in 2007 and we had a lot of players who hadn't won the league then.

"It is easier when you have got experienced players in your camp, the likes of Giggsy, Nev, Scholesy, players who have won the league before.

"There is the experience in there now of having done it before.

"Maybe that is the edge we have got on the other teams.

"It gives you a little bit of an edge but it is not the be all and end all.

"You've got to get momentum. If you've got momentum going into the last few games of the season, then you are in a good position to strike then. That counts a lot."

Ferdinand was handed a 70-minute comeback at West Brom, his first action since the FIFA Club World Cup on December 21 in Japan.

But the 30-year-old insists his back problem isn't a long-term concern.

"It is all right. I could have played a little bit longer but the manager brought me off," he said.

"I am fine, there are no problems. I've just got to keep working hard and keep doing my training."