Klitschko and Joshua train together
Wladimir Klitschko has been sparring with Britain's Anthony Joshua ahead of his fight with Kubrat Pulev on September 6.
The 38-year-old puts his WBA, IBF, WBO and IBO heavyweight titles on the line at the O2 World Arena in Hamburg.
Klitschko, who won gold at the 1996 Olympics, secured a convincing victory over Alex Leapai in April and has been training with fellow Olympic gold medallist Joshua at his training camp.
Anthony Joshua is in camp for sparring. Two Super Heavyweight Olympic gold medalists in one ring that's unique. pic.twitter.com/hLWYvLhGDj— Klitschko (@Klitschko) August 19, 2014
Joshua, who won gold at the London 2012 Olympics, has been victorious in all seven of his fights since turning professional and back in May admitted he was "already thinking about challenging Klitschko in 2015".
Joshua has yet to go beyond two rounds in any of his professional fights - beating Matt Skelton in July at the Echo Arena in Liverpool in his last outing.