The lineal championship in professional boxing, commonly described as "the man who beat the man," is a notional title intended to clarify the modern hodgepodge of sanctioning bodies and alphabet titles. A boxer can only win the lineal championship by defeating the previous lineal champion in the ring. If the lineal champion retires, dies or moves to another division, the vacancy is typically filled by a box-off between two or more top-ranked contenders. The third and most recent interruption of the heavyweight lineage came in 2004, when Lennox Lewis retired and vacated the championship. Only when Wladimir Klitschko knocked out Ruslan Chagaev in June 2009, adding The Ring magazine title to his IBF and WBO belts, did a recognized heir to the lineage emerge. Klitschko defended his WBA, IBF, WBO and Ring magazine heavyweight titles on Nov. 10 with a unanimous-decision win over Mariusz Wach at the O2 World Arena in Hamburg, Germany. It marked Klitschko's 13th title defense.