When Michael Phelps walked away from swimming after the London Olympics, he was adamant that his career was over.

Now it sounds like he's not so sure.

While saying he's never been happier - and that he certainly doesn't miss the grind of what it took to become the most successful athlete in Olympic history - Phelps left the door open to change his mind before the 2016 Rio Games.

"I don't know what's going to happen in the future," Phelps said on Monday. "I don't know what's going to happen tomorrow."

In Barcelona for the world championships, Phelps was coy when asked whether he'll compete at the next Olympics, saying he hasn't planned that far ahead.

That's a striking change from his comments before and after the London Games when he insisted his retirement was set in stone and it had always been his goal to quit swimming before he turned 30.

Phelps will be 31 at the time of the opening ceremony for the Rio Games.

"I don't know. We're in 2013," he said, before adding, "There's nothing in the works right now".

There's plenty of time for a comeback. Phelps would likely want to begin training before the end of the year, which would allow him to get into peak condition leading up to the next world championships in 2015, an important stepping stone for the Olympics.

Phelps certainly isn't training at the moment. He jammed the small toe of his right foot on the edge of a sofa while at home in Baltimore, and aggravated the injury when he played in a golf tournament at Lake Tahoe.

He's wearing a boot cast on his foot to cope with a small stress fracture.

After some sightseeing and promotional appearances, Phelps took in a second night of swimming at the Palau Sant Jordi pool before getting ready to head back to the US on Tuesday.

He was accompanied by his new girlfriend, Golf Channel reporter Win McMurry.

"I have no plans to do anything," Phelps said. "I love what I'm doing now. I'm able to travel so much, play golf. I'm on my schedule.

"I've never been able to have that. I've never been able to do really whatever I want to do. I go wherever I want to go. I see whatever I want to see. It's nice waking up at 10, 11, 12 o'clock in the afternoon. I'm pretty lazy. Besides playing golf, I don't do much."

He does have some projects away from the pool, including a series of swim schools and a foundation devoted to water safety.

He said those are fulfilling projects, but he's still trying to sort out where he wants to go in his life.

"Peter (Carlisle, his agent) asked me where I want to be in one year, five years and 10 years," Phelps said.

"I'm still in the process of putting everything down on paper."

While passionate about golf, Phelps seems to realize it doesn't present much of a career path other than playing in celebrity tournaments.

He once talked bravely about not setting any limits on how far he could go in the sport, even joking that the only way he would be at the Rio Games was as a golfer (the sport is returning to the Olympic program in 2016).

But the game has clearly humbled him since London, despite getting lessons from famed coach Hank Haney as part of a show for the Golf Channel.

"I'm competitive in everything," Phelps said. "But golf has a very slow learning curve. For me to be able to get where I want to be, it's going to take some time to get there.

It's so annoying. It's probably the most humbling thing I've ever done, the most humbling sport I've ever done."

(China Daily 07/31/2013 page22)