BEIJING (AP) — The Latest from the IAAF world championships (all times local):

___

4:35 p.m.

American decathlete Trey Hardee has withdrawn from the competition at the world championships because of a lower back injury.

The two-time world champion hurt his back in the long jump Friday morning, clutching at his left side when he stepped out of the pit after a foul on his third attempt. He struggled in the shot put before pulling out of the competition before the high jump.

Hardee won the event in 2009 and '11.

His agent, Paul Doyle, says Hardee is "undergoing testing at the USATF medical office today to determine the extent of the injury."

___

12:45 p.m.

Defending champion Ashton Eaton leads the decathlon after three events with 2,830 points, including a world championship record in the event in the 100 meters.

The world-record holder opened his program Friday by winning the 100 in 10.23 seconds, the fastest time ever recorded in a world championship decathlon. He jumped 7.88 meters to record the best mark in the long jump and hung onto the lead with the ninth-ranked distance of 14.52 meters in the shot put.

Damien Warner of Canada was in second place with 2,747 points and Rico Freimuth of Germany moved into third with 2,730 after recording the top mark of 15.50 meters in the shot put.

Trey Hardee, a two-time world champion, appeared to injure his back or side in the long jump. After a foul on his third attempt, Hardee clutched at his side when he stepped out of the pit. His best mark of 7.30 had him in ninth place at that point.

Hardee slumped to 26th after the shot put, recording a foul on his first attempt and a mark of 10.20 on his second — his personal best is 15.72 — before passing on his last attempt.

There is a 3 1/2-hour break between the shot put and the high jump. The 400 will be the final event of the day.

___

12:15 p.m.

Defending champion Bohdan Bondarenko and 2013 world championship medalists Mutaz Essa Barshim and Derek Drouin were among the leaders in high jump qualifying at the world championships on Friday.

Nine jumpers cleared 2.31 meters and five more qualified for the final at 2.29 meters.

Drouin, the Olympic and world bronze medalist, didn't miss any attempts at five marks, including 2.31, while Barshim missed his first attempt at 2.29.

Zhang Guowei of China was also faultless to 2.31, while Brandon Starc — the youngest brother of Australian cricket star Mitchell Starc — was twice on the verge of elimination, missing his first two attempts at both 2.26 and 2.29 before clearing those and then clearing a personal best 2.31 on his first attempt.

Olympic silver medalist Erik Kynard of the United States and 2007 world champion Donald Thomas of the Bahamas qualified with marks of 2.29, but 2011 world champion Jesse Williams failed to reach the final.

___

12:10 p.m.

American 100-meter bronze medalist Tori Bowie will not be part of the team's relay pool at world championships this weekend.

In a press release sent Friday, USA Track and Field said athletes were required to participate in a pair of relay camps leading up to the worlds this year. The camps were deemed especially important because of the number of new, inexperienced runners taking part on the team.

Bowie did not attend all the practices, and so she won't be part of the team.

The 4x100 relay final takes place Saturday and the 4x400 is set for Sunday.

The U.S. women sprint relay team has won gold medals at the 2011 worlds and 2012 Olympics and took silver in 2013. But before that, they had trouble with dropped batons and injuries that led to some restructuring of the team's practice and selection process.

___

11:55 a.m.

As they entered the Bird's Nest, Chinese teammates Liu Hong and Lu Xiuzhi discussed whether they would try to outduel one another down the final stretch.

They didn't, with the more experienced Liu winning the 20-kilometer walk ahead of her younger opponent and giving China its first gold medal of the world championships.

"I think both of us would like to have the gold," Liu said. "We talked about whether we would have a fierce ending, then my little sister said, let's just enter the stadium like this (side by side). So not a very fierce ending."

Liu and Lu were virtually assured of gold and silver when they came into the stadium together, leading their nearest competitor by more than 20 seconds.

The only question was who would win gold: the veteran Liu, the world-record holder competing in her fourth world championships, or the 21-year-old Lu, competing in her first?

Experienced counted this time, but both were given the same time — 1 hour, 27 minutes, 45 seconds.

___

11:20 a.m.

Ashton Eaton recorded the best mark in the long jump, following immediately on from his world championship decathlon record in the 100 meters, to lead with 2,070 points after the first two disciplines.

The Olympic and world champion recorded 7.88 meters with his first jump and didn't improve on that. He ran 10.23 in the opening sprint, the fastest time ever recorded in a world championship decathlon.

Eaton, who holds the world record, didn't compete in a decathlon in 2014 but entered the meet as the favorite.

American teammate Trey Hardee, a two-time world champion, appeared to injure his back or side in the long jump. After a foul on his third attempt, Hardee clutched at his side after leaving the pit. His best mark of 7.30 had him in ninth place with 1,847 points.

Damien Warner of Canada produced a personal best 7.65 in the long jump to hold on to second place with 1,992 points. Felipe Dos Santos of Brazil was third with 1,913 points following his season-best 7.54 in the long jump.

___

10 a.m.

China has won its first gold medal of the world championships with Liu Hong winning in the women's 20-kilometer race walk.

Liu won in 1 hour, 27 minutes, 45 seconds, finishing only steps ahead of teammate Lu Xiuzhi. Lyudmyla Olyanovska of Ukraine won the bronze medal, 28 seconds behind Liu.

Liu, who set the world record in the event in June, has a silver and two bronze medals from the previous three world championships.

Italian teammates Eleonora Giorgi and Elisa Rigaudo were in third place at the mid-point of the race but were both disqualified after receiving three warnings for lifting both feet off the ground at the same time.

___

9:35 a.m.

Olympic champion Ashton Eaton started the defense of his decathlon world title on Friday by running 10.23 seconds in the 100 meters, a championship record for the 10-discipline event.

Eaton, the decathlon world-record holder, won the last of four heats to collect 1,040 points, holding off Damian Warner of Canada, who picked up 1,020 points for finishing in 10.31.

Rico Freimuth of Germany ran his season-best 10.51 and was followed by Felipe Dos Santos of Brazil in 10.53 and two-time world champion Trey Hardee in 10.56.

The decathletes were also competing in long jump and shot put during the morning session on Day 7.

___

9:30 a.m.

As expected, Chinese teammates Liu Hong and Lu Xiuzhi were leading at the halfway point of the women's 20-kilometer race walk.

Liu has three medals from the past three world championships, but no gold. She set a world record in the event in June.

Lu has the second-fastest time in the field this year.

Elisa Rigaudo and Eleonora Giorgi, both from Italy, were in a pack of walkers about 25 seconds behind.

___

8:35 a.m.

They're off and ... walking.

The women's 20-kilometer walk is the first event to get going on Day 7 of the world championships, with China favored to win its first gold medal of the competition.

Liu Hong, who holds the world record in the event, is the one to beat.

In the evening session, there will be four more finals, including the women's 200 meters. The men's 110 hurdles is also on the schedule, along with the women's 100 hurdles and the women's long jump.

The decathlon, with Olympic gold medalist Ashton Eaton as the favorite, will also get started on Friday.