Michael Phelps continued his global mystery tour this week with a trip to Sao Paulo, Brazil, to film his newest Subway commercial with soccer legend Pele.

The mystery, of course, is whether Phelps will swim for more gold medals when Brazil hosts the 2016 Olympics.

Phelps coyly evaded the speculation again in Sao Paulo, where he joked to a French news agency that his potential comeback is "the million-dollar question."

Phelps sent a strong signal that he's considering a comeback when he rejoined the international drug testing pool, meaning he could compete in 2014 if he chooses. He has also worked out with longtime coach Bob Bowman at the North Baltimore Aquatic Club in recent weeks.

"I've said 100 times if I feel like coming back ... I could," he told Agence France-Press. "But I'm not saying I am going to."

He has certainly changed his tone in recent months. Where he once declared his love for retirement, he now seems to enjoy fueling speculation with open-ended answers.

This time time at least, Phelps was in Brazil for business and fun. He led a fitness clinic with Pele, and photos showed a grinning Phelps towering over Brazil's most famous athlete.

He has visited Brazil three times in the last 14 months. Will he be there again in three years?

Guess we'll see.