Hudson-Smith seemed on course to win his country’s first gold over the distance since “Chariots of Fire” Eric Liddell in the Paris Games 100 years ago, but he tied up at the end and Hall swept past to win in a personal best 43.40s and give the US their first triumph since LaShawn Merritt in Beijing.

Hudson-Smith bettered his own European record with 43.44s for silver and Zambia’s 21-year-old Muzala Samukonga set his second successive national record with 43.74s to take bronze.

Hall, who took bronze behind Jamaica’s Antonio Watson and Hudson-Smith at last year’s world championship, looked out of contention coming into the final straight a distant fourth as the long-striding Hudson-Smith seemed on course for a first global gold of an injury-plagued career.

He was still well adrift heading into the last 30m but somehow found the energy to drive past everyone and become the fourth-fastest man over the distance, behind world record holder Wayde van Niekerk (43.03s), Michael Johnson (43.18s) and Butch Reynolds (43.29s). Hudson-Smith is now fifth.

Fourth-placed Jereem Richards set a Trinidad and Tobago national record of 43.78s and former Olympic champion Kirani James in fifth was also under 44s in 43.87s.

“Sometimes the journey is better than the outcome,” said Hudson-Smith, who has world silver and bronze and now Olympic silver to his name. “My time is going to come.”

US athletes have now won 19 gold, 13 silver and 11 bronze for 38 medals in the event. Britain are next with two golds and eight medals in all.