The United States have won both 4x100m relays at the world championships in Budapest as their individual superstars Noah Lyles and Sha'Carrie Richardson ran anchor legs to complete triple-medal weeks.
Lyles added the relay gold to his individual sprint double while Richardson had earlier claimed 100m gold and taken bronze in the 200m.
It was a glorious end to the night for the sport's superpower after the earlier disappointment of seeing their highly favoured 4x400m women's team disqualified following a baton failure in the semi-finals.
Despite their rich depth, the US men had not won a 4x100m Olympic final since 2000 and had just one gold from the last seven world championships amid a series of fumbles and disqualifications.
But they were almost faultless on Saturday (early Sunday AEST) as Christian Coleman, Fred Kerley, Brandon Carnes and Lyles won in 37.38 seconds.
Richardson and Gabby Thomas were added to the women's team alongside Tamari Davis and Twanisha Terry and the foursome were superb in running a championship record 41.03.
The much-anticipated last-leg showdown between Richardson and 200m champion Shericka Jackson turned into a non-event as the American collected the baton a metre clear and was never challenged.
Jamaica took silver in 41.21 while Britain claimed bronze with 41.97.
The victory edged the US further ahead in their great women's sprint relay rivalry with Jamaica, having now won six to Jamaica's four from the last 10 world championships.
Baton mishaps are common in the shorter relay, less so in the 4x400, but the US women paid a heavy price for theirs on the penultimate day of the world titles.
They had won seven of the last eight world championships, and the last seven Olympic golds, but were trailing an impressive British team after three legs when Alexis Holmes initially failed to collect the baton from Quanera Hayes.
By the time she eventually got hold of it she appeared to have gone beyond the 'blue box', while Hayes had stepped off the track. Though Holmes recovered to finish second behind the British in the heat, the US were disqualified.
American Chase Ealey successfully defended her women's shot put crown, while China's Gong Lijiao won a record eighth straight individual medal.
Ealey produced her season-best throw in her fifth attempt to win the gold with a 20.43m effort, while Canada's Sarah Mitton took the silver with 20.08m.
Gong, the 2017 and 2019 world champion who is competing at her ninth consecutive global championships, clinched bronze after producing a throw of 19.69m, pipping Portugal's Auriol Dongmo on countback.
Kenya's Faith Kipyegon became the first woman to complete a 1500m-5000m double at the world championships after she raced to victory over the longer distance.
Four days after she won the 1500m, the two-time Olympic gold medallist surged away from Dutchwoman Sifan Hassan down the home straight to cross in 14 minutes 53.88 seconds.
Hassan was second in 14:54:11 while bronze went to Kenya's Beatrice Chebet with a time of 14:54:33.