Gennady Golovkin is a middleweight boxer.
Gennady Golovkin . As of May 2017 , he is ranked as the world 's best middleweight by BoxRec and the Transnational Boxing Rankings Board , and second best by The Ring . Later that year he defeated Marco Antonio Rubio to add the WBC interim middleweight title to his collection , and defeated David Lemieux in 2015 to win the IBF middleweight title . An interim championship is an alternate title that is awarded by the four major sanctioning bodies of professional boxing ( WBA , WBC , IBF , and WBO ) , and in other combat sports such as kickboxing and mixed martial arts .