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.
Occasionally, the champion of a particular weight division is temporarily unable to defend his championship because of medical, legal, or other reasons that are beyond the competitor's control. When this case occurs, two highly ranked contenders may fight for an interim championship of the same weight division – leading to two champions existing in the same weight division simultaneously. Once the original champion is able to return, he must fight against the interim champion in a "unification bout." The winner of this contest is then deemed the "undisputed champion." If the original champion cannot return, or transfers to a different weight division, the interim champion becomes the undisputed champion.
Sanctioning bodies, however, can alter or ignore the interim championship system. One example took place in the WBC's flyweight division in 2005–2006. Pongsaklek Wonjongkam had defended his world title 11 consecutive times. Number-one contender Jorge Arce won an interim championship bout instead of receiving a title shot against Wonjongkam, who continued to defend his world title. Arce defended his interim championship four times before he vacated it in order to move up to super flyweight. Wonjongkam eventually set the flyweight division record for consecutive title defenses, without ever fighting against interim champion Arce.