Wladimir Klitschko has pulled out of his heavyweight world title fight against England's Dereck Chisora for the second time.
The Ukrainian scrapped a December bout against Chisora after suffering an abdominal injury, and Klitschko has now shelved a proposed clash on April 30, with the injury still causing him problems.
"I am very sorry for this final cancellation especially for the fans who had sold out the SAP Arena (in Mannheim)," said Klitschko.
Medical tests showed that Klitschko had not fully recovered from the injury he had sustained in training and the April date was too soon for a fight.
"As things stand now it is difficult to predict when he will have fully recovered. A fight in April with all the intensive preparation he needs is too big a risk," said Klitschko's doctor, Hans-Wilhelm Mueller-Wohlfahrt.
The 26-year-old Chisora beat Sam Sexton in September to add the Commonwealth heavyweight title to his British crown.
Zimbabwe-born Chisora has won all of his 14 fights as a professional, nine through knockout, compared to 34-year-old Klitschko's 55 wins and three defeats.
British champion Chisora now appears unlikely to face the IBF and WBO champion, as Klitschko's camp are believed to be in advanced talks with WBA champion David Haye about a possible unification fight in the summer.