George Bovell of Trinidad and Tobago qualified fastest in the 50-meter freestyle preliminaries at the London Olympics, with defending champion Cesar Cielo right behind.
Bovell touched in 21.77 seconds on Thursday to win the sixth of eight heats in swimming's glamour event.
Cielo finished the furious one-lap sprint in 21.80, with teammate Bruno Fratus third at 21.82.
Anthony Ervin of the U.S. was fourth at 21.83 in his return to the Olympics after a 12-year absence. He tied American Gary Hall Jr. for the gold at the 2000 Sydney Games before leaving the sport.