Takeru 'Tsunami' said he can only open his mouth to make a gap the size of a fingertip after being diagnosed with jaw arthritis.
In an entry on his blog entitled Occupational Hazard, Kobayashi said: "My jaw refused to fight any more."
The injury occurred only a week after the slender 29-year-old started training to win his sixth
straight title at the annual July 4 Nathan's Famous Hot Dog Eating contest on New York's Coney Island.
"I feel ashamed that I couldn't notice the alarm bells set off by my own body," he said. "But with the goal to win another title with a new record, I couldn't stop my training so close to the competition.
"I was continuing my training and bearing with the pain but finally I destroyed my jaw."
Gee, hard to believe scarfing down all those hot dogs has negative ramifications, isn't it?