Montantes' career began in 1990 with a win against NorbertoRiviera followed by a loss to Jose Vilarino. There was initially no hint of the success to come. However, following the loss to Vilarino, Montantes put together a string of 22 straight wins against ever-improving competition. His last two fights were losses to well-known fighters Acelino Freitas and James Crayton. His final record was 28 wins and 4 losses.