The challenges for Dayron Robles come from all angles, and the Cuban hurdler knows all about the possibilities for upsets or bad luck.

Last year, Robles was disqualified in the world championships after defeating his Chinese rival Liu Xiang in the 110-meter hurdles final. Back and right-leg injuries then kept him out of the world indoor championships in March.

"I want to enjoy everything about the Olympics, as if I had never participated before," Robles said. "I want to win, but I also want to take in the whole event so that I can share with athletes from different countries and cultures. This is a beautiful, emotional thing."

One of the premier showdowns in London is expected to pit Robles against Liu for gold. Waiting in the wings for an upset are two Americans, Jason Richardson and David Oliver.

Robles is trying to take the spotlight off his rivalry with Liu and he has repeatedly called the two Americans his biggest threats. They are both talented and battle-hardened in the high-wire world of hurdling.

"You have to respect anyone who reaches the Olympic final," Robles said. "They (the Americans) are the ones who have the most power in the 110 hurdles. They will not give in easily. Anyone who has gone through the US qualification system is ready to beat anyone at any stage. ... Americans are the kings of the event."

In the world championships last year in South Korea, Robles was disqualified for obstructing Liu in the final. Instead of Robles, the victory went to Richardson, while Liu was awarded second.

Robles is the defending Olympic champion, winning gold after Liu pulled out with a right foot and right hamstring injury during the first round of qualification at the Bird's Nest in Beijing.

He also set the world record of 12.87 seconds earlier that year, taking the record from Liu. Since then, the best time in the event has been 12.89 by Oliver.

"I feel some pressure, but that's good because it's not overwhelming pressure," Robles said.

"I'm enjoying the training and aware of the responsibility I have to myself, my family, my coach and all my people."

Robles said he has recovered from the injuries that kept him out of the world indoors in Istanbul. "I'm sorry for not having taken part in the world indoors," he said. "I feel relaxed and motivated and the decision has no psychological effect. I hope it doesn't affect me physically and that I can be in top shape in London."