DAYRON ROBLES
The bespectacled 21-year-old from Guantanamo in Cuba could be the one to break a billion hearts.
In majestic form, Robles has even been ungracious enough to lower Liu's world record to 12.87 seconds last month.
He has swept through the European Grand Prix circuit to become the first man to run the 110m hurdles inside 13 seconds on four occasions in a single season.
'I know my race against Liu will be one of the greatest attractions of the Games,' Robles says.
3 OTHERS TO WATCH IN TRACK
At last year's world championships, American Allyson Felix became only the second woman to win three golds: in the 200m and the 4x100m and 4x400m relays. She could do it again.
Known for her late burst of speed and for training at altitudes of 4,000m, Ethiopia's Tirunesh Dibaba owns the 5,000m world record and is the reigning two-time world 10,000m champion.
Bernard Lagat, who quietly became a naturalised US citizen in 2004, is the first athlete to win both the 1,500m and 5,000m at the world championships last year.