Yuzo Kiyota wore a surgical mask when he arrived at a media conference in Germany this week.
The Japanese fighter, who challenges WBO super-middleweight champion Robert Stieglitz in Dresden on Saturday night, explained he was concerned about picking up an illness.
"It's common for Japanese athletes to protect themselves from infection. That's why I wear the mask," he said.
He added: "Robert Stieglitz is a good fighter but I want to win by a knockout."
The champion said he was concerned about Kiyota’s aggressive style. "I’ll have to use my physique and technical ability and apply plenty of pressure. I've had a look at his fights. He boxes aggressively and goes forward. He is physically strong.”
Stieglitz will fight in the city for the first time since beating Mexico's Enrique Ornelas on points in 2010. "In my last fight in Dresden, the audience was great, so it's like boxing at home here,” he said.
The 29-year-old Kiyota, boxing outside Japan for the first time in his career, has won 21 of his 26 fights by knockout and has lost only three times.
But he is untested at this level. In his last bout against an experienced fighter, he lost on a first-round technical knock-out against Jameson Bostic of the US.
Stieglitz regained the super-middleweight title he lost on a unanimous decision in August last year when he stopped Arthur Abraham in the fourth round of their rematch last March.
The defeat to Abraham was the 32-year-old champion's only loss in the last four years. But even though he has won 44 of his 47 professional fights, Stieglitz says he has to prove himself against Kiyota.