ATHLETICS: Reigning world and Olympic 100m hurdles champion Sally Pearson is unlikely to race again until July after re-injuring her hamstring.

Pearson suffered what is expected to be diagnosed as a grade-one hamstring tear while contesting the 4x100m relay at a meet in Sri Lanka on Sunday.

It was the same injury which caused Pearson to miss the Australian domestic season.

But Australian head coach Eric Hollingsworth remained confident the 26-year-old would be back to full fitness in time to defend her world crown in Moscow in mid-August.

"We're taking every precaution with Sally, so now we don't expect to see her competing until July," said Hollingsworth.

"If we can get her through a good set of races in July, there should be no problem from there on in.

"We just have to be ultra-cautious because it's the second injury.

"We'll take our time with the rehab.

"Sally will make sure she does all the right things."

Pearson had been planning to compete over the hurdles for the first time this year at a meet in Manchester on May 25.

The injury has ended hopes of Australia qualifying a women's 4x100m relay team for the world titles in Moscow.

Australia will also be unrepresented in the women's 4x400m relay at the world championships following a hamstring injury to Anneliese Rubie and the unavailability of Caitlin Sargent.

John Salvado
AAP