WBC heavyweight champion

Frustrated Wilder threatens to retire

Undefeated Wilder beat Stiverne in January 2015 to win the WBC belt - the only one of his 38 fights to go the distance - and has successfully defended his title five times since.

However, a proposed defence against Luis Ortiz at the Barclays Center in Brooklyn fell through when the former WBA champion failed a drug test.

It was followed by Anthony Joshua's Principality Stadium showdown against Kubrat Pulev being changed late on when the Bulgarian suffered a shoulder injury. IBO, WBA, IBF champion Joshua takes on Carlos Takam in Cardiff on Saturday.