MOSCOW (AP) — Olympic champion Ashton Eaton ran a season's best in the opening 100 meters Saturday to take the early lead in the decathlon at the world championships.

Behind Eaton's 10.35 seconds, Damien Warner of Canada took second place, edging defending champion Trey Hardee before the 10-event competition went into the long jump.

The clash between Eaton and Hardee over the opening weekend is expected to be one of the highlights of the championships.

Late Saturday, Usain Bolt will run in the 100 heats and Olympic champion Mo Farah of Britain is going for gold in the 10,000, seeking to become the first European in 30 years to take the world title in that event.

The women's marathon is the only other final on the opening day.