Ukrainian boxer Oleksandr Usyk / Photo from

The World Boxing Association (WBA) has ordered unified cruiserweight champion, Ukrainian boxer Oleksandr Usyk (16-0, 12 KO) to defend his titles against Russia's Denis Lebedev (32-2, 23 KO).

"The WBA has ordered Usyk to make a mandatory defense against former titlist Denis Lebedev and on Tuesday scheduled a purse bid for the bout for March 28 at the WBA offices in Panama City," the ESPN sports news portal said.

Read alsoUkraine's boxer Usyk named ESPN 2018 fighter of year – media

The sides will have to negotiate until March 28, then they will hold a purse bid with a 75/25 split between Usyk and Lebedev, respectively.

The minimum bid will be $400,000.

Denis Lebedev is a former unified cruiserweight world champion, having held the WBA title from 2012 to 2018, and the IBF title in 2016. In August 2016, Lebedev was ranked as the world's best active cruiserweight by the Transnational Boxing Rankings Board.