Heavyweight champion Wladimir Klitschko had to receive emergency treatment after eating a chicken salad.
The IBF, WBA, WBO and IBO champion had to call an ambulance during the night and was put on a drip after being knocked out by the salad he enjoyed in a Hamburg restaurant.
The 36-year-old Klitschko was laid low for several days last week after the evening meal in the fashionable St Pauli district, reported a German daily newspaper, Bild.
The Ukrainian, who lives in Hamburg, was one of a group of four who were all ill after eating the same food at the same restaurant.
Klitschko, who retained his titles when he beat Mariusz Wach in Hamburg on November 10, was back on his feet two days after the illness. He has since attended an event in Ukraine.