The Italians featuring 100m champion Marcell Jacobs won their country's first medal in the event at the Olympics since 1948.
The Italian 4x100m relay quartet of Olympic 100m champion Marcell Jacobs, Lorenzo Patta, Eseosa Desalu and Filippo Tortu raced to victory to win their first gold in the event since London 1948.
Lead-off runner Patta handed the baton to Jacobs, who produced a storming run down the back end, with Tortu on the anchor leg crossed the line in a new Italian record of 37.50 seconds. Great Britain, pipped at the line by 0.01s, claimed the silver medal, with Canada bagging bronze, clocking 37.70.
Jacobs will bow out of the Games as a double Olympic gold medallist in the sprint events while Canadian sensation Andre de Grasse won his third medal at Tokyo 2020. De Grasse opened his campaign at the Games with a bronze medal in the 100m final before being crowned Olympic 200m champion.
Great Britain had one hand on their first gold medal in the event since Athens 2004, with Nethaneel Mitchell-Blake gaining a slight lead in the home straight.
But Tortu, on his outside, would not be denied as he produced a blistering anchor for Italy inching ahead to out dip Mitchell-Blake.