The Olympic rowing champion Nathan Cohen has had to withdraw from the men's quad scull at the world champs in Korea, after suffering a recurrence of an irregular heartbeat.
Cohen, who won a gold medal in the double scull in London last year, suffered the problem during yesterday's heats.
He also suffered an episode while competing on Lake Karapiro in April.
In yesterday's heat he experienced lack of strength and power as the race went on with the men's quad finishing in fifth place.
The quad will now go through the repechage series with Karl Manson repalcing Cohen in the boat.