Updated 5 p.m. ET
DAEGU, South Korea -- Running the fastest times in the 100 and 400 meters, American Ashton Eaton took the lead in the decathlon Saturday after the opening five events at the world championships.
Eaton, who won the U.S. championships in June, leads with 4,446 points. Defending world champion and teammate Trey Hardee is next with 4,393 points and Oleksiy Kasyanov of Ukraine is third with 4,310.
Hardee led after three events, but Alkesey Drozdov of Russia briefly took the top spot after having the second best performance in the high jump, clearing 2.14 meters.
Eaton, who was third after four events, blew away the field in his heat and had by far the best time in the 400, finishing in 46.99 seconds. Hardee finished fourth in the same heat, while Drozdov fell to sixth overall after finishing 25th in the fifth.
In the 100, Eaton ran 10.46 to lead the field after the opening event.
Hardee, the current world outdoor and indoor champion, said he remained upbeat despite spending the night in second place.
"I'm at the top, and that is all you can ask for," Hardee said.
The 27-year-old Hardee said he felt "a little bit fuzzy in the morning" but insisted he found his rhythm in the afternoon.
On Sunday, the athletes will compete in the 110 hurdles, discus, pole vault and javelin before concluding with the 1,500.
"I'm just excited about tomorrow. He knows how to win. I know how to win," Hardee said of the budding rivalry with Eaton. "I just have to turn the switch on a little bit sooner."
The Americans have won gold in the three of the last four world championships. Most expect it will come down to a dual between Hardee and Eaton, the world indoor record holder in the heptathlon.