The American women's sprint relay quartet pulled off a stunning upset over Jamaica at the World Championships on Saturday while a flubbed baton handover proved costly for the U.S. men's team as it finished second to Canada.
Jamaica was anchored by new 200-meter champion Shericka Jackson but Twanisha Terry ran a terrific final leg to bring home the hosts' 10th gold medal in Eugene.
"It's just an amazing feeling," Terry said. "The race was electrifying. The stadium went crazy."
Germany took a surprise third-place finish after Britain's Dina Asher-Smith pulled up injured.
The United States had looked set to retain the men's title until Elijah Hall and Marvin Bracy lost time with a slow exchange, the latest disappointment for a country with incredible depth of sprinting talent.
Andre De Grasse, the Olympic 200-meter champion, beat Bracy to the finish line while Britain collected bronze.
"It's special to win here. There are many Canadians cheering us on. It's not on home soil, but it felt like it," De Grasse said.
Portugal's Pedro Pichardo (triple jump) and Kenyan Emmanuel Korir (800-meter) added world titles to their Olympic crowns but Canada's Damian Warner, also a gold medallist in Tokyo, suffered injury heartbreak in the decathlon.
Pichardo jumped a world-leading 17.95-meter to take gold ahead of Burkina Faso's Hugues Fabrice Zango and China's Olympic silver medallist Zhu Yaming.
Korir produced his trademark devastating kick to clinch the 800-meter title with Algerian Djamel Sedjati taking a surprise silver ahead of Canada's Marco Arop.
Warner was in firm control of the decathlon after the first four events but his hopes of winning a first world title were dashed after an injury in the 400-meter, with Puerto Rico's Ayden Owens-Delerme moving into the overall lead.
Anderson Peters of Grenada beat Olympic champion Neeraj Chopra to retain his javelin title with a throw of 90.54-meter, with Czech Republic's Jakub Vadlejch third.
Ethiopia's Gudaf Tsegay charged down the final straight to win the women's 5,000 meters while world record holder Letesenbet Gidey and Olympic champion Sifan Hassan missed out on a podium finish.
Allyson Felix helped the U.S. women's 4x400-meter relay team qualify for the finals as they finished with the fastest time of the heats.
Their male counterparts, winners of seven of the past eight world titles and eight of the past 10 Olympic golds, also cruised into the finals, which will take place on the last day of the championships on Sunday.