Former Brazil striker Ronaldo has pledged to get back in shape with a view to playing for US club Fort Lauderdale Strikers.
Ronaldo recently became a minority owner with the Strikers, who play in America's second-tier North American Soccer League (NASL).
"I will train a lot, and if the coach needs me, maybe [return to playing]," he told a news conference.
The 38-year-old last played with Brazilian club Corinthians in 2011.
"It's easy to get in shape - you have to train," three-time World Player of the Year Ronaldo added.
"To play a soccer game you have to be in very good shape so I will try.
"I'll start another challenge and I'm sure it will help the league and it will help the team and help soccer in America."
Ronaldo won the World Cup with Brazil in 1994 and 2002, finishing as top-scorer in the latter tournament with eight goals.
He also played for Barcelona, PSV Eindhoven, Inter Milan and Real Madrid during a decorated club career.
Former Spain striker Raul, a team-mate of Ronaldo at Real Madrid, joined New York Cosmos, who also play in the NASL, in October at the age of 37.