Images from the World Athletics Championships in Eugene, Oregon, on Saturday, Day 9.
A flubbed final handover cost the United States gold in the men's 4x100 metres relay on Saturday as Canada surged down the final straight to take the world title.
The Americans looked set to retain their crown until the last changeover between Elijah Hall and Marvin Bracy, who lost time with a slow exchange.
Canadian anchor Andre De Grasse did not waste the opportunity and passed Bracy on the final leg.
Britain finished with bronze.
It was a phenomenal final push from De Grasse, the Olympic 200m champion who suffered an early season foot injury and was off the track during a crucial training period due to COVID-19 ahead of the worlds.
He withdrew from the 200m earlier in the meet and failed to qualify for the 100m final.
"I'm happy to be here," he said. "I'm just happy to come out here."
It was the first world gold in the event for Canada since 1997.
The United States stuck to the same lineup from Friday's semi-final and got off to a strong start from Doha 100m champion Christian Coleman, who executed a serviceable handover to Noah Lyles.
Bracy attempted to recover the lost time from the final pass of the baton but the United States once again fell short.
Despite their depth of sprinting talent American teams have won only three world titles since 2001 and failed to top the podium at the Olympics since Sydney.
US women shock Jamaican superstars to win sprint relay
Jamaica fielded the three medallists from the women's 100 metres in Saturday's World Championships sprint relay but that was still not enough to prevent a super-slick U.S. quartet taking gold to raise the biggest cheer of the week at Hayward Field.
Jamaica looked formidable after bringing in their "big three" - Shericka Jackson, Shelly-Ann Fraser-Pryce and Elaine Thompson-Herah - with lead runner Kemba Nelson the only survivor from their semi-final team.
The United States introduced Abby Steiner to join Melissa Jefferson, Jenna Prandini and Twanisha Terry, and after a superb series Terry ran a terrific anchor leg to bring them home in 41.14 seconds - the fifth-fastest in history.
Jamaica were second in 41.18 - the sixth-best ever - after losing fractions on a couple of stretched changeovers.
Britain were in the medal hunt until 200m bronze medallist Dina Asher-Smith pulled up injured at the end of her third leg, allowing Germany to storm through for a surprise bronze in 42.03.
Jamaica and the United States had each won four of the previous eight world titles and between them eight of the last 10 Olympic golds.
Saturday’s head-to-head was as mouth-watering as any of those, with the Americans hoping their well-honed teamwork could make the difference against a squad that they hoped might just be a metre of pace down after their gruelling individual campaigns.
It proved to be the case as Jamaica twice had to slow a touch to collect the baton, as the Americans made no mistakes.
Prandini ran a brilliant third leg and Jamaican anchor Jackson, two days after her 200m gold, could make no impression on Terry as the United States took their Eugene gold tally to 10.
It was a stunning consolation for Steiner, who came into the championship as a medal favourite in the 200m but finished fifth in the final.
Nigeria set an African record of 42.22 to come fourth while Spain posted a national record 42.58 in fifth having also set a new mark in the semis.
Portugal's Pichardo eases to triple jump gold
Portugal's Pedro Pichardo continued his dominance in the men's triple jump on Saturday by adding his first World Championships title to the Olympic gold he won in Tokyo.
The 29-year-old, a two-times world silver medallist for Cuba before switching allegiance to Portugal, jumped a world-leading 17.95 metres on his first attempt to take the top spot.
"The opening 17.95m ended up being the winning mark. I opened strongly," Pichardo said. "This world title was elusive to me.
"I had two silver medals and tried to win gold and achieved it today. This title means a lot. I am progressively winning all possible titles, from Olympic gold to the world title."
Pichardo becomes Portugal's first world champion in the event since Nelson Evora in Osaka in 2007.
Burkina Faso's Hugues Fabrice Zango finished a distant second with an effort of 17.55m.
China's Olympic silver medallist Zhu Yaming claimed bronze with 17.31m.
American Will Claye, who won silver in 2017 and 2019, finished 11th, while compatriot and four-times World champion Christian Taylor failed to qualify for the final.
Masterful Korir wins 800m gold in style
Kenya's Olympic champion Emmanuel Korir ran a textbook tactical race to win the world 800 metres title on Saturday as he peaked at just the right time after a wretched season.
Korir arrived in Eugene with barely a race to his name but ran himself into form through the rounds.
In Saturday's final he sat near the back of the tightly-bunched pack for 600m before putting his foot down, sweeping past most of them on the bend then overhauling fading leader Marco Arop on the home straight.
He won in one minute, 43.71, with Algerian Djamel Sedjati producing a storming finish of his own to take a surprise silver in 1:44.14 ahead of Canada's Arop (1:44.28).
"I was expecting a faster race, but I won and I am very happy," said Korir. "I knew there were some guys close behind me in the last 100m. I was expecting someone to come, but no one did.
"It's been a long wait. I failed in 2017 and 2019 but I've made it now," added Korir, who failed to get past the semi-finals in the last two worlds.
Arop ran a brave race, hitting the front early and stretching the field, and said his bronze felt like redemption after failing to reach the Olympic final when fancied for a medal.
Korir's win took Kenya's gold medal tally in the event to seven, though this was their first since 2015.
Wyclife Kinyamal, the second-fastest in the world this year behind injured British absentee Max Burgin, finished last, with the third Kenyan finalist, 17-year-old Emmanuel Wanyonyi, fourth.
Ethiopia's Tsegay holds on to win 5,000m gold
Ethiopia's Gudaf Tsegay held off late challengers to win the women's 5,000 metres as World record-holder Letesenbet Gidey faded down the straight to miss the podium.
Tokyo bronze medallist Tsegay traded the lead with compatriot Gidey, the world 10,000m champion, throughout the race until the pack took off for the final lap.
The Netherlands' 5,000m Olympic champion Sifan Hassan, known for her ferocious kick, picked up the pace before delivering a challenge with 200m to go as she wove to the inside, but could not maintain her speed as Tsegay charged down the final straight.
"I have been training well for 1,500m and this helps spring on the home stretch," said Tsegay, who collected silver in the 1,500m earlier in the meet. "This win is for all of Ethiopia.
"I was trying to control the race coming from the first place during the run so it was very hard for me ... I felt in shape and my victory confirms it was a good plan."
Kenyan Beatrice Chebet moved up in the final 200m for silver and Ethiopian Dawit Seyaum finished with bronze.
"It was a matter of tactics. I was well positioned," said Chebet. "This medal will make a good difference for me."
It was the fourth gold for Ethiopia in Eugene, Oregon, who have 10 medals total and sit behind the United States in the medals table.
After the race a fan ran onto Hayward Field holding what appeared to be a Tigray flag and picked up both Tsegay and Gidey before being removed by security.
A conflict erupted in November 2020 between rebellious forces from the Tigray region and the Ethiopian government.
