LONDON (Reuters) - Rebecca Soni made the perfect start to the defense of her 200 meters breaststroke title when she set the fastest time in Wednesday's heats at the London Olympics.

The American showed no lingering effects of her narrow loss in the 100 breaststroke final two days ago as she glided her way through the pool to win her morning heat in a time of two minutes, 21.40 seconds.

She was more than a second, a big margin in elite swimming, ahead of her nearest rival, Denmark's Rikke Pedersen.

The top 16 advanced to Wednesday night's semi-finals from which the fastest eight will go through to Thursday night's final.

(Reporting by Julian Linden; Editing by Greg Stutchbury)