S2·E7 Wandering... Like a Wild Beast

Without a club willing to organize a bout against him, Joe's career seems over for certain. Even Danpei says, "Joe Yabuki, the boxer is dead" and urges him to retire. Unable to accept his career may be over, Joe is at a loss. Then, he receives an invitation from Yoko to see Carlos Rivera's fight. What kind of man and boxer is Carlos Rivera?