BEIJING (AP) — Usain Bolt was back on familiar territory on Tuesday, running his favorite event and showing off why he is the greatest 200-meter runner of all time.

After the intense pressure that accompanied his come-from-behind win over Justin Gatlin in the 100 on Sunday at the world championships, Bolt was all smiles as he coasted into the semifinals of the 200. Gone was any worry about injuries, about his rival, or about stutter-steps that marred his 100 semifinal heat.

"It means a lot more to me," Bolt said of the 200, the event in which he is a three-time defending champion and two-time Olympic gold-medalist.

Easing up with 50 meters to go and jogging at the end, Bolt crossed in 20.28 seconds, tied for 13th overall. In the heat after him, Gatlin powered to a time of 20.19. Gatlin also outran Bolt in the 100 heats.

"I'm a little worried about my fitness," said Bolt, now 29 years old. "I'm tired and my legs are still sore, but I'm going to have another bath tonight and hopefully tomorrow, I'll be there."

Like Bolt, David Rudisha has been struggling with injuries for the past two years but still came up golden in Beijing.

The Kenyan won the 800 meters at the London Olympics in a world-record time and had not been back to his best since. At the Bird's Nest, Rudisha rekindled that Olympic spirit, again front-running from the start to hold off Adam Kszczot after the Pole attempted to pass 250 meters from the end but left himself boxed in.

Soon, Rudisha was out of reach and finished in a slow 1 minute, 45.84 seconds, almost five seconds off his world record.

Nicholas Bett added to the super night for Kenya with victory in the 400-meter hurdles title, winning in 47.79 seconds. Bett had never broken 49 seconds at sea level before heading to China, but now has a national record after his run in the outside lane.

The Americans, who had five of the top six places on the 2015 list heading into the championships, narrowly missed out on a medal, highlighting another dismal night for the top nation in the sport.

In the medal standings, Kenya leads with four gold medals and nine overall, with the United States back in sixth place with one gold and six overall.

Second is Britain, and like Rudisha, it was a 2012 Olympic champion who came through when Greg Rutherford won his first world title in the long jump with a season-best leap of 8.41 meters. Former world indoor champion Fabrice Lapierre of Australia overtook two Chinese jumpers for silver at 8.24.

American contender Jeff Henderson had the season-leading mark of 8.52 heading to China, but finished ninth, further underscoring the bleakness of the U.S. performance.

In the other finals on Tuesday, Genzebe Dibaba of Ethiopia pulled away halfway through the 1,500-meter final and never let anyone close again as she added the world title to her world record. She will be seeking to complete a 1,500-5,000 double on Sunday.

And Cuba made its first medal a golden one when Denia Caballero won the discus title with her first throw, giving her a rare victory over defending Olympic and world champion Sandra Perkovic.

While Bolt was starting to chase his 10th gold at the worlds in the 200, Allyson Felix was closing in on her ninth, seeking to match the Jamaican's current record. Felix produced one of her trademark smooth runs to coast into the final of the 400 in 49.89 seconds, her top time this season.

She was the only competitor to beat the 50-second mark, with Shericka Jackson coming in second at 50.03 seconds. Shaunae Miller of the Bahamas won the first semifinal heat in 50.12, ahead of Christine Day of Jamaica in 50.82.

Defending champion Christine Ohuruogu of Britain won the second semifinal heat in 50.16.

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