The footballer, Nigerian Malachy Ekene Obinwanne, 24, is being held at Krabi Jail.
A Krabi policeman confirmed today that the alleged rape of the American woman took place about 2am on Thursday, close to Nopparathara beach.
The officer said that a police patrol saw a young woman in distress and were told by her that she had been raped.
The woman was taken to a medical clinic in Ao Nang and later to Krabi Hospital, the officer said.
Obinwanne was arrested at his rented home at 9am on Friday and is now in jail.
US Embassy officials had asked for details of the alleged rape to be kept from the media, the officer said.
Krabi FC, which plays in Division One with FC Phuket, has a Yamaha League match in Bangkok tomorrow.