Few matchups were more anticipated at the 2008 Beijing Olympics than the 110-m-hurdles showdown between Cuba’s Dayron Robles and China’s Liu Xiang. Liu pulled out with an injury, leaving Robles — the event’s world-record holder (12.87 sec.) — to breeze to the gold medal. Since then, injuries have also hampered Robles, 25, who has failed to break 13 sec. in recent years. But he’ll still be the favorite in London. And the rivalry with Liu should be even more intense after Robles’ first-place finish in last year’s world championships was disqualified when judges ruled that his arm had obstructed the Chinese hurdler.