The US, as expected, dropped Quincy Wilson, the 16-year-old who struggled badly in the heats, but did not bring in individual 400m champion Quincy Hall, instead adding 400m hurdles champion Benjamin to run the final leg.
Chris Bailey took them out but handed over in third to Vernon Norwood who ran a stormer in the heats and repeated it in the final to send Bryce Deadmon off in the lead.
Botswana’s Anthony Pesela, however, closed the gap to set up a dramatic finale.
Tebogo the 200m champion who was drafted in at the last minute to run the first leg for Botswana in the heats on Friday, sat on Benjamin’s shoulder and looked poised to pass him entering the final straight.
Benjamin’s one-lap speed endurance showed, however, as he held him off to win in an Olympic record two minutes 54:43.
It was a remarkable 19th gold in the event for the U.S.
Botswana, bronze medallists in Tokyo, took silver in an African record 2:54.53 with Britain taking bronze in a European record 2:55.83.
The race was of such high quality that fourth-place Belgium and fifth-placed South Africa set national records, and Japan in sixth set an Asian record.
A class apart
The United States blazed to the gold medal in the Olympic women's 4x400 metres relay on Saturday, clocking the second quickest time in history and stretching the country's remarkable victory streak in the event to eight in a row.
Fielding a star-studded foursome featuring Olympic champions Sydney McLaughlin-Levrone and Gabby Thomas, the Americans clocked three minutes 15.27 seconds, narrowly missing the world record set by the former Soviet Union in 1988.
A week after Femke Bol led the Dutch to victory in the mixed 4x400 relay with a remarkable anchor leg, the gap was too great for her to make up and the Netherlands had to settle for silver in 3:19.50. Britain claimed bronze in 3:19.
Jamaica were in third spot after the opening leg, but Andrenette Knight dropped the baton after bumping Ireland's Rhasidat Adeleke on the second leg.
Shamier Little put the U.S. in front before handing off to McLaughlin-Levrone, who put 30 metres on the field with her sizzling 47.71 seconds lap and the only question from that point was who would win silver.
Thomas handed off to Alexis Holmes about 40m ahead clear and she led her team home.
