Olympics-Athletics-American Eaton sprints to decathlon lead

(Adds quote) By Scott Malone RIO DE JANEIRO, Aug 17 (Reuters) - American defending champion Ashton Eaton relied on his blazing speed on the track to take a solid lead in the Olympic decathlon on Wednesday, trailed by German Kai Kazmirek and Canada's Damian Warner. After finishing second to Warner in the opening 100 metres, when the 26-year-old Canadian ran an Olympic best of 10.3 seconds, Eaton leapt into the lead with a 7.94m long jump and held the position despite mediocre performances in the shot put and high jump. But the 28-year-old resident of Eugene, Oregon, really showed his speed in the day's final event, the 400m. Eaton quickly tore through the pack, accelerating through the bend to and powering down the home straight to finish with a time of 46.07 seconds. "I feel OK about day one," said Eaton, who is married to Canadian heptathlete and Olympic bronze medallist Brianne Theisen-Eaton. "The whole thing so far is going, I just don't know how to say it, smooth I guess." Kazmirek, 25, was Eaton's nearest threat in the 400m, finishing with a time of 46.75 that was good enough to catapult himself into second and bumping 26-year-old Warner to third. Warner pronounced himself disappointed with his first-day performance. "There was so much more that I could have gained. It's up to me," said Warner, who finished fifth in the 2012 London Games. "I was expecting to come out here and score a lot of points on day one and that didn't happen." But the crowd's clear favourite was Brazil's Luiz Alberto de Araujo, 29, who won his 400m heat with a time of 48.14, charging down the home stretch shoulder to shoulder with Cuba's Leonel Suarez, who trailed by 0.01 second at the line. Earlier, De Araujo had first caught the crowd's attention with a 15.26m third-place shot put throw, though that was not enough to offset a poor showing in the long jump, leaving him in ninth on the day. France's Kevin Mayer led the shot put with a 15.76m throw, leaving him in fourth at the day's end, with American Jeremy Taiwo in fifth overall thanks to the best high jump performance, clearing 2.19m. The event continues on Thursday, with the 100m hurdles, discus, pole vault, javelin and 1,500m. (Editing by Ed Osmond)