Kenya's Olympic 800m champion David Rudisha is facing a three-week layoff with injury, sending the east African nation into panic mode and sparking fears over Rudisha's challenge at the world championships.

Rudisha picked up a knee injury running in Central Park in New York City, undermining his preparations for August's world championships in Moscow. 

"He (Rudisha) was jogging inside Central Park when he realised something was the matter with his knee," Colm O'Connell, the Irish high school teacher who coaches Rudisha, said on Tuesday.

"Two initial investigations were done, first in the USA and also in Germany, and we decided that he takes a three-week rest."

We were already panicking, but we were assured by medical specialists after the second scan that he does not need an operation. But he needs between two to three weeks to rest

Colm O'Connell, Rudisha's coach

He will definitely miss Kenya's national championships, which start in Nairobi on Thursday, but his participation in the world championships is not expected to be in doubt, even though he might be forced to sit out Kenya's world championships trials.

"We are not sure yet whether he will be ready by the time of the trials," O'Connell said.

"But being a world champion, we are expecting that he will get an automatic selection (known as a wildcard) to the championships.

"He does not need to run at the trials to be selected for the world championships. He will only run if he feels comfortable.

"We were already panicking, but we were assured by medical specialists after the second scan that he does not need an operation. But he needs between two to three weeks to rest."

Rudisha, 24, who won the Olympic title in a world record time of 1:40.91 in London last year, ran a season leading 1:43.87 in the first IAAF Diamond League meeting this year, in Doha last month.

He also won in New York City but skipped the Eugene, Oregon, leg.

Kenya will select its team for the world championships on July 13.

The country's athletics chiefs are crossing their fingers on Rudisha's fitness.

"We really need him in the team to Moscow because of his experience and attitude. We hope he recovers in time," Athletics Kenya's vice president, David Okeyo, told reporters.

Kenya boasts other top 800m runners - Olympic bronze medallist Timothy Kitum and Antony Chemut - but their pedigree is below that of Rudisha.

Source: Reuters