Mikkel Kessler's boxing comeback has been delayed after the former world super middleweight champion contracted Lyme disease.
Kessler had been expected to return to the ring next month but will now be unable to end his absence of over four years until March 2018.
The 38-year-old has been released from hospital and is completing a course of antibiotics after being struck down by the illness.
"I started to feel ill around four weeks ago. I was tired, my muscles were aching and I was unable to train," Kessler said.
"At that point, I still had no idea what was causing it. I had blood tests, which showed nothing, and it wasn't until I had a spinal fluid test that the doctors were able to identify the problem.
"I'm not sure exactly when or where I was bitten by the tick, but I'm just thankful the bacteria was caught early and hopefully there will be no long-lasting effects.
"Obviously, I'm disappointed to have to delay my comeback. I want to thank my fans for their support and patience. I hope to be ready to return to the ring early next year, and I promise to repay their support with a great victory!"
"I've had fighters suffering from many different injuries and illnesses in the past but this is a first for me," said promoter Kalle Sauerland.
"I know Mikkel is bitterly disappointed, but his health must come first. We are now set for March and will announce venue and opponent in the coming weeks. It will take more than a tick to stop The Viking Warrior!"
Kessler holds a 46-3 record, his last fight a loss to Carl Froch in a rematch in London in 2013.