Joshua must face Pulev after Klitschko retirespublished at 11:06 British Summer Time 3 August 2017
BBC Sport
The retirement of former heavyweight world champion Wladimir Klitschko means that Anthony Joshua must now face mandatory challenger Kubrat Pulev before 2 December, or risk being stripped of his IBF belt.
The Ukrainian, 41, was knocked out in the 11th round by current champion Joshua, from Watford, at Wembley Stadium in April.
Joshua, 27, had hoped Klitschko would sign his rematch clause for a proposed fight in Las Vegas on 11 November.
Bulgarian Pulev, 36, has a record of 25 wins and one defeat, which was against Klitschko in 2014.