LONDON - Prince William may be closer in line to the British throne, but brother Prince Harry bested him at a finish line.

Harry, William and William's wife, Kate, the duchess of Cambridge, raced a 50-meter sprint against each other Sunday at London's Queen Elizabeth Olympic Park as they promoted a mental health campaign called Heads Together .

Cheered by track stars and amateur runners training for April's London Marathon , Harry crossed the line a stride ahead of his older brother. William and third-place Kate hugged at the finish.

William, perhaps aware he would be beat by his more athletic sibling, had quipped moments before the start: "Oh, my hamstring!"One spectator, women's marathon world record-holder Paula Radcliffe, joked afterward that William should have been disqualified for straying into Kate's lane.