Yamanishi held on to win by 15 seconds from fast-finishing Vasily Mizinov on the Doha seafront. Third went to Perseus Karlstrom of Sweden. Japan has won two gold medals at the world championships, both in the walks.
Russia started Friday's events with three medals and finished the night with six after Mizinov's silver and a 2-3 finish in the men's high jump. That matches the total medal tally of the Russian team in 2017, when they also competed as neutrals due to punishment for past doping offenses.
Steven Gardiner, the silver medalist in 2017, has done one better, winning gold in the men's 400 meters at the track world championships.
The Bahamian clocked 43.48 seconds Friday in Doha.
Anthony Zambrano of Colombia claimed silver for his first world medal, leaving Fred Kerley of the United States to settle for bronze.
Top-rated American Michael Norman failed to advance from the semifinals.
The crowd in Qatar is delighted after Mutaz Essa Barshim retained his world title in high jump.
Barshim jumped 2.37 meters, the best in the world this year, and his victory was sealed when Russians Mikhail Akimenko and Ilya Ivanyuk both failed all three attempts at that height.
Barshim has a personal best of 2.43, two centimeters short of the world record, but opted to stop jumping at 2.37 and start the celebrations.
Every jump from Barshim was cheered uproariously by a large crowd of Qataris in the nearest stand, some displaying a large banner bearing his image. The crowd Friday is much larger than at any previous day of the championships after many free tickets were distributed.
Cuba's back on top in the women's discus throw.
Denia Caballero lost her world title to Croatia's Sandra Perkovic in 2017, but on Friday her compatriot Yaime Perez beat them both to take the gold.
Perez threw 69.17 at her fifth attempt to snatch the lead from Caballero, whose best mark was 68.44. Perkovic, the Olympic champion, had to settle for bronze with 66.72 after fouling her last three throws.
Conseslus Kipruto of Kenya remains the man to beat in the 3,000-meter steeplechase — but only just.
The 2016 Olympic and 2017 world champion overhauled Ethiopian 18-year-old Lamecha Girma on the final stretch to win by just one-hundredth of a second in a photo finish.
The winning time was 8 minutes 1.35 seconds, the fastest by anyone this season. The silver was Girma's first ever medal at a major championships.
Soufiane El Bakkali took the bronze for Morocco.
Dalilah Muhammad has set a new world record of 52.16 seconds in winning the women's 400-meter hurdles, narrowly beating fellow American Sydney McLaughlin.
Muhammad had set the earlier record of 52.20 when she beat McLaughlin to win the U.S. national title in July in Des Moines, Iowa.
McLaughlin closed down Muhammad on the back straight, but Muhammad showed strong speed on the exit of the second turn and held her lead to the line to win by .07 seconds.
Rushell Clayton of Jamaica took bronze in 53.74.
The Olympic bronze medalist Ashley Spencer briefly looked on course to seal a U.S. podium sweep — something no country has managed at these championships — but faded on the final stretch and was sixth.
There will be no third medal for Andre de Grasse in the men's 4x100 relay.
Even having de Grasse, the 100-meter bronze and 200 silver medalist, on the anchor leg couldn't push Canada into the final as his squad finished sixth.
The U.S. came close to botching changeovers in both the men's and women's heats but still qualified for both finals.
Michael Rodgers slowed to a near-halt before his changeover with last-leg runner Cravon Gillespie, who had to sprint hard to make the final behind Britain and Brazil. South Africa won the other men's heat in a new African record time.
In the women's heats, Dezerea Bryant and Teahna Daniels of the U.S. struggled to hand over the baton, but eventually made it work as their team won the heat in 42.46 seconds ahead of Trinidad and Tobago.
Australian women's relay hopes ended when third-leg runner Maddie Coates fell and took teammate Nana Adoma Owusu-Afriyie down with her. France and Brazil were disqualified.
Jamaica qualified fastest from the women's heats in 42.11 in part thanks to a fast leg from 100-meter world champion Shelley-Ann Fraser-Pryce. Britain was second and China third.
The finals are Saturday.
Timothy Cheruiyot of Kenya secured his place in the men's 1,500-meter final in front of the largest crowds yet at the Doha track world championships.
The silver medalist in 2017, Cheruiyot won his semifinal in 3 minutes 36.53 seconds in a race where Norway's European champion Filip Ingebrigtsen finished just seventh and failed to qualify.
Poland's Marcin Lewandowski won the other heat in 3:36.50 ahead of Kenyan Ronald Kwemoi and Ingebrigtsen's brother Jakob.
Defending champion Elijah Manangoi of Kenya is not racing due to an ankle injury.
The Khalifa International Stadium has its biggest crowds of the championships so far, drawn by ticket giveaways and the promise of watching Qatar's Mutaz Essa Barshim contend for a medal in the men's high jump.
After days when showpiece events like the men's and women's 100 finals were greeted by rows of empty seats, places are so in demand that organizers have removed awnings over sectors of the stadium to increase capacity.
The world record could fall as Dalilah Muhammad and Sydney McLaughlin of the United States do battle once again in the women's 400-meter hurdles on day eight of the world track and field championships.
Muhammad set a new world record of 42.20 seconds when she beat McLaughlin at the U.S. nationals in July. McLaughlin was the faster of the two Wednesday as both won their semifinals.
Also Friday, Fred Kerley of the U.S. is the favorite for the men's 400 after fellow American Michael Norman was eliminated in the semifinals. The 2011 world champion Kirani James of Grenada could also challenge for gold.
Medals are also on offer in the men's high jump and women's discus, as well as the men's 3,000-meter steeplechase and 20-kilometer race walk. The men's and women's 4x100 relays start with heats.
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