David Rudisha's defence of his world 800 metres title in Moscow next month is in doubt because of a knee injury, the Kenyan's coach said on Wednesday.
"He is progressing on well, but I doubt if he will heal early enough to resume training for the world championships," Rudisha's coach Colm O'Connell said by telephone from Iten, some 400 km north west of Kenyan capital Nairobi.
"We will give a comprehensive report on his condition after a week then we will communicate to the IAAF (International Association of Athletics Federations) and Athletics Kenya.
"His wild card (for the championships) is an advantage, but we are praying that he responds well to treatment," Irishman O'Connell said.
Rudisha, who set a world record of 1:40.91 winning the Olympic title last year in London, picked up the knee injury running in Central Park in New York City.
The 24-year-old is being treated in Germany and is expected to miss the east African nation's trials on Saturday.
Rudisha's manager James Templeton has not responded to enquiries regarding the athlete.
Kenya will name the final team for the August 10-18 world championships after the trials.
Anthony Chemut, Job Kinyor and Olympic bronze medallist Anthony Kitum are the likely candidates for the two-lap race in the event Rudisha's injury rules him out of the worlds.