MADRID (AP) — Cristiano Ronaldo is really serious about keeping his options open for the future. Not even Barcelona or Manchester United's rivals in England are off limits.

Ronaldo told The Associated Press on Thursday that he knows it would be "very complicated" to play for these clubs, but it's something that the Real Madrid star doesn't rule out either.

He said nothing is certain in soccer, so he will not close doors to any leagues or teams, not even Madrid's biggest rival.

"It's a little more difficult, but...," he said, with a long pause, not dismissing the possibility.

"There are things that you kind of already have an idea, that to play one day for Barcelona would be almost impossible, or to play for another English club other than Manchester, it's very complicated," he said. "But that's not 100% guaranteed. As I said before, there are no certainties in football."

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In his interview with the AP, the Portugal forward made it clear that when it's time to decide about his future, he will consider all options on the table.

"Everything is open, all leagues," he said. "I may end my career here with Real Madrid. I'm just being honest. I don't know what's going to happen tomorrow. If I was 75% certain, I would say so, it wouldn't be a problem. But I have no idea."

Speaking before the launch of his new product with nutrition partner Herbalife, Ronaldo said he may even decide to be somewhere else other than Europe, and that it's not impossible for him to be playing in the United States' Major League Soccer.

"Right now I don't see myself playing in the American league, but that's right now," he said. "In two or three years I may think differently."

He said that in the future he may be at a stage of his life in which he might prefer playing in the U.S., instead of the more traditional European leagues.

"These are always difficult questions to answer because we never know what's going to happen tomorrow," he said. "And as a football professional, this is always an unknown, so I prefer to stay in the present. The present is good and I'm enjoying being at Real Madrid. But in a few years I don't know how I'm going to be thinking."

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Ronaldo has a contract with Real Madrid until 2018, but there has been widespread speculation about him leaving the Spanish club–despite having become its all-time leading scorer. Those rumors gained ground after his brief sideline meeting with Paris Saint-Germain coach Laurent Blanc in a recent match at the Santiago Bernabeu Stadium, but Ronaldo has been downplaying any immediate move out of Madrid.

"When it's closer to ending my contract I'm going to have to make decisions, whether it's staying at Real Madrid or going to another club or ending my career in a few years," the 30-year-old Ronaldo said.

"It's normal. That's why I'm not worried, because I know that everything has a beginning and everything has an end. I'm ready for that. I'm ready to stay at Real Madrid, to leave, to end my career when it's time. It's part of my job."

The Portugal star, voted the best player in the world three times, played six seasons with Manchester United before joining Madrid in 2009.

Here are other topics addressed by Ronaldo:

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PORTUGAL AT EURO 2016

"Portugal has never been the favorite. It's normal, it never won a major title with its senior team, so obviously it's not a favorite. But in football there are always surprises and anything can happen. So I'm hopeful that this time Portugal can come up with a brilliant performance. We have a good team, with 20 good new players and a very good coach (Fernando Santos).

"We have all the ingredients to win an important competition. There's always the luck factor, especially in these short competitions. That's always important when it comes to the groups, the teams that you have to play against. But I'm hopeful and I think that Portugal has a good chance. We have a good team and good players who are ready and motivated."

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BALLON D'OR

"Obviously, I don't have control over who wins it. It's not like the Golden Boot, which is based on statistics. This one is about votes, so it's harder. Sometimes people don't look at what you did in the past, just what you are doing now, so it's very complicated.

"I don't think it would be a surprise if I won it, I personally had an excellent season. In terms of numbers, this was my best season. But it wasn't in terms of titles, for sure. Whoever wins it will be a deserving winner."

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MADRID WOES

"It's complicated when the team is going through a moment of instability. We want to make the fans happy every day, but it's difficult, obviously. But after the storm comes the calm and I hope that's what we will find now. We have won five straight matches after the loss to Barcelona. We had the setback against Cadiz (in the Copa del Rey), but we are going through a good moment.

"Personally too, I am feeling good, I'm more confident, and the goals and the good performances are happening. So I'm at ease and hopeful of always being able to do more."

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RETIREMENT

"I'm not thinking about that just yet. I feel I'm strong, I'm fast. Even faster than some of the 21-year-old and 22-year-old players that I've been playing against. And I hope that it stays this way."

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