Football great Pele denounced FIFA President Sepp Blatter's belief that some top players are treated like slaves by their clubs.
Blatter was giving his assessment of Cristiano Ronaldo's standoff with Manchester United over a move to Real Madrid when he said that players seeking a transfer should be allowed to leave.
The top-earning Portugal winger concurred with Blatter's "modern slavery" comments, which upset football's first black superstar.
"You are a slave if you work without a contract or you don't get paid," said Pele, a three-time World Cup winner with Brazil, which abolished slavery 120 years ago.
"If you have a contract then in any job you have to finish the contract.
"I think that when he finishes his contract, then he should be free to go wherever he wants to go."
Ronaldo has almost four years left on his Old Trafford contract and, while no transfer request has been submitted, the 23-year-old English footballer of the year has spent the summer angling for a transfer to Madrid.
Pele was in Stoke on Saturday for a charity match in aid of former England goal-keeper Gordon Banks' foundation.