SYDNEY - The 110 meters hurdles has rarely been one of the glamour events of athletics but that could all change when the three fastest high hurdlers of all time come together at the World Championships in South Korea.

Cuban Dayron Robles and China's Liu Xiang are back from injury and ready to take on powerful American David Oliver with expectations high that they could produce the most spectacular showdown on the Daegu track.

Largely in the absence of the two most recent Olympic champions, Oliver has dominated the last two seasons and went unbeaten in 18 finals from the end of August 2009 to May this year.

The 29-year-old's grip on the event has slipped over the last few months, however, as a resurgent Robles (twice) and Liu beat him in Diamond League meetings.

China's Liu is the only one of the trio to have won the world title - in Osaka in 2007 - but the 28-year-old has rarely been fit since as he continues to deal with the foot problem that led to his dramatic exit from the Beijing Olympics.

A former world record holder and 2004 Olympic champion with a career best time of 12.88, Liu has competed sparingly this year but managed to end Oliver's formidable winning streak in his home town of Shanghai.

Oliver soon avenged the defeat in Oregon by running the only sub-13 second time of the year (12.94) but Liu's time of 13.00 in second place confirmed that he was firmly back in business.

"Liu Xiang is in good form, his health, technique and stamina are in a good state as well," China's head coach Feng Shuyong told reporters in Beijing on Thursday.

"His injury has recovered gradually. He got good results this year because the injury is gradually getting better so he has been able to train more systematically.

"But the biggest challenge for him might be running three races in two days for the first time since 2008."

That was the year that Robles took both Liu's world record, when he ran 12.87 in Ostrava, and his Olympic title in Beijing but the 24-year-old Cuban's career has also been disrupted by injuries since.

This season,?Robles has made a low profile return to the track but beat Oliver in Paris and London and is now targeting the one major title that has eluded him.

"I am very pleased with the results that Dayron had in Europe, twice beating the American David Oliver, which is an important psychological point for him," his coach Santiago Antunez told Reuters by telephone from Madrid.

Part of the attraction of the potential showdown in this most technical of track events is the contrast in styles between the three.

Oliver, a former American football player, is all power and muscle, relatively slow to get off the mark but not afraid to knock down a few hurdles as he bulldozes his way to the finish line.

The bespectacled Robles is the arch technician, smoothly gliding over the hurdles, while the whippet-like Liu's greatest quality was always his fierce competitiveness which enables him to make up ground over the last 15 metres.

Liu has taken a step out of his run up to the first hurdle this year in an attempt to compete with the other main contenders but it remains a work in progress, according to Feng.

"His new technique of seven steps to the first hurdle has still not reached the level he had with eight," the coach said. "There is still room for improvement between the first and the second step."

With so little room for error in the high hurdles, there is always a chance that none of the three will claim the title with in-form American Jason Richardson looking most likely to provide what would be quite an upset.

To do that, though, the dreadlocked 25-year-old is likely to have to run considerably faster than his personal best of 13.08 seconds.