VALENCIA, Spain (Reuters) - Title favourite Dayron Robles suffered a shock exit in the first round of the 60 metres hurdles at the indoor world championships on Saturday after being left in the blocks in his heat.

The 21-year-old Cuban appeared to think there had been a false start and jogged out of the blocks only to see the rest of the field striding away from him.

Robles, the second fastest 60-metre hurdler in history who has threatened Colin Jackson's 14-year-old world record of 7.3 seconds, tried to make up the lost ground but ended up trailing across the line last in 8.53 seconds.

He threw himself on to the track in frustration and sat with his head in his hands, bemoaning his misfortune.

"It can't be...It just can't be," he said as he left the stadium.

Robles, who won silver at the last world indoor championships in Moscow, has clocked nine of the year's 11 fastest times.

Olympic 110 metres hurdles champion Liu Xiang, who was in the lane beside Robles and finished second in the heat behind Latvia's Stanislavs Olijars, said that a lack of experience may have contributed to the error.

"I feel really sorry for Dayron," Liu told reporters. "I got a really fast start and I feel that this put him off. I think it has been a lack of experience on his part because in case of doubt it is better to continue running until you hear the second gun.

"It is a shame because I wanted to run against him. He's my reference in the 60 metres hurdles."

(Editing by Clare Fallon)