Wladimir Klitschko has issued a "fight me" video message ultimatum to heavyweight rival David Haye.
The 34-year-old said the Briton, who has twice pulled out of bouts against the Ukrainian and his brother Vitali, should stop running from him.
"Don't be a coward. David, twice you cancelled against the Klitschko brothers (last year). But now the time has come," the IBF, IBO and WBO champion, whose brother Vitali holds the WBC crown, said in a video message posted on his website.
Haye retained his WBA title on April 3 after stopping American John Ruiz in the ninth round.
A Klitschko v Haye fight is the one many fans would like to see given that the two brothers will not fight each other.
Haye pulled out of a scheduled fight with Wladimir last year, citing an injury, although it was more a case of the two sides and their promoters failing to reach a deal.
Wladimir retained his belts with a knockout victory against Eddie Chambers in March while Vitali takes on European champion Albert Sosnowski of Poland for the WBC crown on May 29.