Triple Olympic champion Usain Bolt's remaining 200m season may be in jeopardy because of a strained Achilles tendon, the Jamaican said on Wednesday.

"I have no idea but I am praying on it," Bolt told a news conference when asked if he would run another 200m this season.

"The doctor said in four weeks I should be OK."

Bolt has switched to the 100m from the 200 for Thursday's Diamond League meeting in Lausanne to avoid further injury.

"He (the doctor) does not want me to run the bend until I am 100 percent fit because it would put more stress on my Achilles tendon," the world 100 and 200m record holder said.

Bolt developed a tightness in his left Achilles tendon in late May after running a 300m in Ostrava. He has not run since and only resumed speed work last week.

He has the year's fastest time for the 200, having run 19.56 seconds in Kingston in May.

"I have no clue (about fitness), Bolt said. "The doctor said the foot is getting better."

But talking about his only real work on the bend, Bolt said: "I aggravated the injury and had to stop.

"In the morning it (the tendon) is kind of stiff," the world's fastest man said, "but it goes away."

The 23-year-old said he faced a similar situation when he begins to warm up but eventually the pain and stiffness go.

Bolt thought Thursday's race, his second 100m of the season, would be a good test.

"I just wanted to see where I am at," Bolt said. "I know I can always go a good time because I am still in good shape."

A bigger test will come next week when he is scheduled to race compatriot and former 100m world record holder Asafa Powell in Paris on July 16.

"He (Powell) is the one in very good shape," Bolt said of Powell, who has the year's fastest time over 100 at 9.82 seconds.

"If Asafa beats me, I will not say because I am injured ... I don't think anybody is unbeatable this season."