British and Commonwealth super-middleweight champion George Groves has pulled out of his WBO title fight against Robert Stieglitz.
The 24-year-old was lined up to challenge the champion in Germany on May 5 but he picked up an unspecified injury while training in Northern Cyprus.
And Groves is optimistic the problem will only cause a "short delay" to the fight.
"We tried to work through it, but soon realised I wouldn't be able to perform the training needed to prepare for this fight," said Groves in a statement released by promoters Hayemaker Boxing.
"After immediately coming back to London and seeking medical advice, I hope this problem will be quickly sorted and cause only a short delay.
"I am truly sorry to everyone who will be affected by this.
"This is without doubt the toughest decision I have ever had to make, and I am gutted, but nothing worth having is given away.
"It has only made me more determined to achieve my goal of becoming world champion."
The setback is the second time in a little more than a month that Groves has pulled out of a fight citing an unspecified medical complaint.
On March 12, the Londoner withdrew from a scheduled defence of his British title against Kenny Anderson at Wembley Arena.
