Moscow: Ashton Eaton added the world title to his Olympic decathlon gold medal and Brittney Reese reigned over the long jump for the third time in a row in a golden day for the United States.
Later Sunday, Usain Bolt was to make his return to the final of the 100 meters, two years after he was disqualified for a false start in the biggest setback on his sterling career.
Eaton blazed away from competition on the second and final day of the 10-discipline event and was able to cruise home in the 1,500 meters to claim the biggest title which still eluded him.
A standout 110 hurdles to start the day allowed him to confidently build an increasing lead and he sealed it with a big javelin throw in the penultimate event.
Finishing sixth in the final race in the muggy heat of about 30 degrees C (86 degrees F) was more than enough for Eaton, who won with 8,809 points.
For Reese, it was another world championships of living dangerously. Reese only reached the final as the last qualifier.
On Sunday though, a huge jump of 7.01 meters on her second attempt was good for gold, beating Blessing Okagbare of Nigeria by 2 centimeters.
At 26, the gold made Reese the defining long jumper of the past half decade with six straight major international titles.
She celebrated wearing a T-shirt that read "Unleash the Beast," referring to the nickname she earned as a relentless competitor.
It might also refer to Bolt, who has the chance to claw his way back to the 100 gold medal.
In the 100 semifinals, the Jamaican superstar was slow out of the blocks and had to work to chase down Mike Rodgers before winning his heat in 9.92 seconds.
"I got it done, so that's the good thing," Bolt said.
The reigning Olympic champion will have to deal with 2004 Olympic gold medalist Justin Gatlin, the only racer to have beaten him this season. The American won his heat in 9.95.
With a time of 9.90 seconds, Nickel Ashmeade led a Jamaican 1-2-3 in qualifying followed by the two Americans, setting up a thrilling opener of the U.S.-Jamaican sprint rivalry at major events.
All eyes will be on Bolt, though. In the only major flaw of his sterling career, he let the gold slip out of his grasp in South Korea in 2011 when a rare false start cost him a second consecutive triple at the world championships.
He made up for that in London last year and is favored to win another string of 100, 200, 4x100 titles in Moscow.
Host nation Russia won its first gold medal at the championships when 20-year-old Aleksandr Ivanov won the 20-kilometer walk in a sweltering race, beating Olympic champion Chen Ding.
As so often in the walk, disqualifications for running or technical infractions were crucial. Two kilometers from the finish, Erick Barrondo of Guatemala edged ahead of Ivanov, not knowing that he had just received his disqualification card.
Besides Eaton and Reese, the United States is also looking at a possible sweep in the 110-meter hurdles after its three top runners reached the semifinals.
Olympic gold medalist Aries Merritt, defending champion Jason Richardson and the season's fastest man, David Oliver, all won their heats.
Merritt and Richardson combined for a 1-2 finish at last year's London Olympic.
"I wouldn't mind if we swept up the hurdles," Richardson said, anticipating that with Ryan Wilson also through, they could even go 1-2-3-4.
"I'm coming on this team with an amazing group of athletes. Aries is formidable with the world record. David, former American record holder. Of course, Ryan, who's a veteran of the game," Richardson said. "Feel bad for fourth place, but, hey, things happen."
Hansle Parchment of Jamaica, a bronze medalist at the London Olympics, finished fifth in his heat but made it through as the one of the fastest losers.
While all eyes will be on Bolt in the 100 meters later Sunday, the women sprinters started their qualifying heats in the morning humidity at a near-empty Luzhniki Stadium.
Most favorites never pushed themselves in advancing to the semifinals, but American runner English Gardner went well under 11 seconds in 10.92 to be the top qualifier.
"We've trained through a lot of meets, and finally, like I always say, the lion got let out of the cage and I just went out there and had some fun," Gardner said.
Defending champion Carmelita Jeter, Alexandria Anderson and Octavious Freeman made sure all four Americans advanced.
Kerron Stewart and two-time Olympic champion Shelly-Ann Fraser-Pryce led the Jamaican contingent of four into the semifinals.
The other finals on Day 2 are the women's discus throw and the women's 10,000.