The 23-year-old Parchment had the world leading time of 13.05s when he twisted his ankle, while warming up for the sprint hurdles finals at the National Athletic Championships on the evening of June 23. After being out for two weeks, he returned to training and has been steadily recovering from the injury.

"There is still some discomfort in the ankle but he has been training well," said Parchment's coach, Fitzroy Coleman.

"He hasn't been doing much hurdling but the plan is to get his fitness as close as possible to what it was before he was injured."

Prior to the injury Parchment had been rounding into the kind of form that made him one of the favourites for the sprint hurdles in Moscow. On June 1, Parchment ran his world-leading time in Eugene, Oregon. Since that time only the USA's David Oliver has run faster with a 13.03 run in Lausanne on July 4. It could mean that Parchment may still be in the hunt for a medal but Coleman believes that that is a difficult call to make.

"He is not as sharp but his progress has been encouraging," he said, adding that it is difficult to say how close the Olympic bronze medalist is to the form that he had earlier in the season. Without races, he says, one would have to be a fortune teller to be able to make that determination.