BEIJING (AP) The Latest from the IAAF world championships (all times local):
The United States has been disqualified from the men's 4x100-meter relay.
The Americans finished second in the race behind Jamaica on Saturday at the world championships, but the team was stripped of their place because the last exchange was out of the zone.
Instead of the Americans taking silver, China was moved up to second and Canada took bronze.
Usain Bolt won his third gold medal of the world championships, anchoring Jamaica's 4x100-meter relay team to victory to match his haul at the Bird's Nest in the 2008 Olympics.
Bolt won the 100- and 200-meter finals, beating Justin Gatlin in both sprints, and added the relay victory on Saturday to successfully defend all three world titles he won in Moscow in 2013.
Jamaica won in 37.36 seconds, with a United States team containing Gatlin taking silver in 37.77 and China getting an unexpected bronze in 38.01.
The Jamaicans completed a sweep of the sprint relays with the women, anchored by 100-meter champion Shelly-Ann Fraser-Pryce, also winning.
Piotr Malachowski won the discus throw with a best mark of 67.40 meters to claim his first world championship title and give Poland a third gold medal in throwing events in Beijing.
Malachowski was a silver medalist at the 2008 Olympics at the Bird's Nest and a two-time silver medalist at the worlds.
Philip Milanov set a Belgian record to take silver at 66.90 in Saturday's final. Robert Urbanek of Poland earned the bronze medal with a mark of 65.18 on his fifth attempt.
Three-time world champion Robert Harting, who also won the discus at the London Olympics, missed the meet because of injury.
Shelly-Ann Fraser-Pryce anchored Jamaica to the second-fastest time in history to win the women's 4x100-meter relay in 41.07 seconds on Saturday.
The United States took silver in 41.68 seconds, with Trinidad and Tobago collecting bronze in a national record 42.03.
The United States holds the world record of 40.82 seconds.
Ashton Eaton broke his world record in the decathlon, running 4 minutes, 17.52 seconds in the 1,500 meters to finish with 9,045 points and retain his world title.
It was the first world record at the 2015 championships at the Bird's Nest, the venue of the 2008 Olympics.
The Olympic and world champion had 8,216 points after nine events, a lead of 256 over second-place Damian Warner of Canada, and needed to go under 4:18.25 in his last event to surpass the world mark of 9,039 he set in Oregon in June 2012. His personal best in the 1,500 in a decathlon is 4:14.48.
Eaton, who hadn't competed in a full decathlon in two years, started with a championship record in the 100 when he recorded 10.23 in his opening event. He added a decathlon world record in the 400 - running 45.00 seconds in his last event Friday.
Maria Kuchina of Russia won her first world championship title in the high jump on Saturday, beating two-time world champion Blanka Vlasic and Olympic champion Anna Chicherova on a countback.
The 22-year-old Russian, last year's world indoor champion, was clear with her first six attempts to a personal best 2.01 meters. She missed all three jumps at 2.03 - waiting for her turn until the two more experienced rivals went out at the same height.
Vlasic, competing again after left heel surgery in 2012, also won the Olympic silver medal at the Bird's Nest in 2008. Her only miss until she fouled out was on her second height at 1.92.
Chicherova had one miss each at 1.97 and 2.01 and finished again with the bronze medal, the same color she collected at the 2008 Olympics and at the 2013 world championships in Moscow.
Mo Farah of Britain won his third consecutive world title in the 5,000 meters on Saturday and completed a long-distance double after his victory in the 10,000.
With blistering acceleration, Farah swept past Caleb Ndiku in the finishing straight to win in a slow 13 minutes, 50.38 seconds, 1.37 seconds over the Kenyan. Hagos Gebrhiwet of Ethiopia took bronze.
Farah hung back in last place for the first two kilometers before moving to the front to orchestrate yet another win at the worlds.
Marina Arzamasova of Belarus surged ahead of defending champion Eunice Sum with about 250 meters to go and held on to win the 800 in 1 minute, 58.03 seconds at the world championships on Saturday.
Melissa Bishop of Canada won the silver, crossing in 1:58.12, and Sum, who hadn't lost a race in 2015 leading into the championships, finished third.
Ashton Eaton is back on course to break his decathlon world record after throwing 63.63 meters in the javelin, the ninth event of the competition.
The Olympic and world champion has 8,216 points - a lead of 256 over second-place Damian Warner of Canada - with only the 1,500 to run later Saturday. A time of 4 minutes, 18.25 seconds will be enough to surpass his world record of 9,039 points. His personal best in the 1,500 in a decathlon is 4:14.48.
Rico Freimuth of Germany was in third place with 7,862 points.
Ashton Eaton extended his lead after the eighth event of the decathlon at the world championships.
Eaton, however, slipped slightly off world-record pace when he failed to clear his personal best height in the pole vault on Saturday.
Eaton has 7,423 points after clearing 5.20 meters. With only the javelin throw and the 1,500 meters remaining, the Olympic and world champion is 45 points behind pace for his own world record.
Damian Warner of Canada lost ground in the pole vault, missing all three attempts at 4.90 and slipping 254 points behind Eaton.
Rico Freimuth of Germany is third with 7,115 points.
There's one showdown left between Justin Gatlin and Usain Bolt - in the 4x100-meter relay later Saturday.
Gatlin, who has two silver medals in the first two meetings with the Jamaican, has been feeling the effects of all this racing.
''I hope he's tired, too,'' Gatlin said.
While Gatlin ran in Saturday's preliminaries, Bolt took the morning off. Didn't matter. Like the Americans, the Jamaican team, headlined by Asafa Powell, finished first in its heat.
On the women's side, the American team also won its heat, though there was a bit of a bobble in the exchange between the third and fourth runners, Jenna Prandini and Jasmine Todd.
The U.S. has dropped the baton in big events before, and has spent years trying to work out the snags. This time, America's only female sprint medalist, Tori Bowie, was left out of the relay pool because she did not participate in all the required American training camps leading to Beijing.
Practice makes perfect. At least some of the time.
''There was a little misstep,'' Todd said. ''At the end of the day, they put me in such great position, it didn't really affect anything.''
The Jamaican teams advanced fastest in both men's and women's 4x100-meter relay heats at the world championships on Saturday.
Usain Bolt, who won the 100-200 sprint double, didn't run in the Jamaican team that won the second heat in 37.41 seconds. France surged into second place with a strong anchor leg from Jimmy Vicaut to finish in 37.88, narrowly ahead of China, which qualified in an Asian record 37.92.
The American men won their heat in 37.91, with Justin Gatlin running the second leg and exchanging the baton with Tyson Gay. Britain was second in 38.20.
Shelly-Ann Fraser-Pryce anchored the Jamaican women's team to victory in the first heat in 41.84 seconds, the world-leading time this season.
Allyson Felix ran a strong second leg to help the Americans win the next heat in 42.00, the second-fastest qualifying time.
Sanya Richards-Ross finally got her turn on the track at world championships.
''Bitter, bittersweet,'' the American called it.
The 2012 Olympic champion at 400 meters failed to qualify for her signature event and came to China this year as part of the 4x400 relay team. She has been hanging at the team hotel for two weeks, waiting to race.
She ran the third leg Saturday and increased the lead to help the Americans easily advance to Sunday's final.
A win there, and she could leave the Bird's Nest with a gold medal to write a nice closing chapter to a difficult stay in Beijing.
She says she's having a good time, and enjoying mentoring the younger runners on the team. But she wants to do more running next year at the Olympics in Rio de Janeiro.
''I'm going to train so hard,'' she said. ''I don't want to feel like this again.''
Defending champion Ashton Eaton stayed within world-record range after seven events in the decathlon, amassing 6,451 points after the discus throw.
Eaton, who set the world record at 9,039 points in 2012, threw 44.34 meters and had a 131-point lead of Damian Warner of Canada. Warner cut Eaton's overnight lead by 42 points with better marks in the 110-meter hurdles and the discus throw on Saturday.
Rico Freimuth of Germany was in third place with 6,266 points, recording the best mark of 50.17 meters in Group A of the discus throw.
The pole vault, javelin throw and 1,500-meter race are still to come in the decathlon.
Matej Toth of Slovakia won the longest event at the world championships, capturing gold in the 50-kilometer walk in 3 hours, 40 minutes, 32 seconds.
Toth, the 2014 European silver medalist, broke away from the other walkers shortly after the start and raced nearly the entire course on his own, stopping only briefly for a bathroom break.
He came into this year's world championships in top form, setting the third-fastest time in history in his native Slovakia in March.
It's the first gold ever for Slovakia at the world championships.
Jared Tallent of Australia, a two-time Olympic silver medalist, finished more than a minute behind Toth in second. Takayuki Tanii of Japan took bronze. Defending champion Robert Heffernan of Ireland was fifth.
Veteran walker Jesus Angel Garcia of Spain, competing in his 12th world championships at the age of 45, finished in ninth place. He won gold more than two decades ago at the 1993 worlds in Stuttgart.
The U.S. teams qualified fastest for the men's and women's 4x400-meter relay finals at the world championships.
The American women led at every split and finished in 3 minutes, 23.05 seconds to beat Britain (3:23.90) and France (3:24.86) in their heat on Saturday. Nigeria had the second-fastest qualifying time, winning the first of the women's heats in 3:23.27.
In the second of the men's heats, Jamaica led at the first two changeovers before the Americans rallied to win in 2:58.13. Trinidad was second in 2:58.67, edging Jamaica by 0.02.
Britain won the earlier men's heat in 2:59.05.
Matej Toth of Slovakia leads the 50-kilometer walk just past the halfway point, widening his lead over his nearest competitors to 55 seconds.
Toth, who has the third-fastest time in history, passed the 30-kilometer mark in 2 hours, 13 minutes, 14 seconds.
Defending champion Robert Heffernan of Ireland and two-time Olympic silver medalist Jared Tallent of Australia were in a group of walkers behind Toth, alongside Zhang Lin of China and Japanese teammates Takayuki Tanii and Hirooki Arai.
Ashton Eaton leads the decathlon by 165 points after six events, placing second to Damian Warner of Canada in the 110-meter hurdles on Saturday.
Warner won the last of the decathlon sprint hurdles heats in 13.63 seconds, reducing the margin by eight points to Eaton, who recorded 13.69.
Eaton, the Olympic and world champion, had 5,718 points with the discus throw, pole vault, javelin and 1,500 meters to go.
Warner was in second with 5,553 points and Rico Freimuth of Germany was third with 5,392.
Yordani Garcia of Cuba crashed in the last heat of the hurdles, slipping to 25th place. Two-time world champion Trey Hardee withdrew on Friday after injuring his back in the long jump.
Matej Toth was leading the 50-kilometer walk after 15K in the world championships.
Toth, who has the third-fastest time in history, passed the mark in 1 hour, 7 minutes, 28 seconds and was 39 seconds clear of Jared Tallent of Australia, a two-time Olympic silver medalist.
Defending champion Robert Heffernan of Ireland, Mario Jose Dos Santos of Brazil and Lukasz Nowak of Poland were part of a group a further 10 seconds off the pace.
The 50-kilometer walk got under way Saturday morning, minus the only Russian entered in the competition.
Alexander Yargunkin was entered in the race but did not start amid reports that he did not travel to China because of the recent doping scandal engulfing race walking in Russia.
Jared Tallent, the two-time Olympic and two-time world championship silver medalist from Australia, was among the early leaders.