Jemima Sumgong became the first Kenyan woman to win the Olympic marathon, beating Eunice Kirwa of Bahrain.
Ethiopia’s world champion Mare Dibaba took the bronze medal as her compatriot and race favourite Tigist Tufa pulled out before the halfway mark.
London Marathon winner Sumgong, 31, finished in two hours 24 minutes four seconds to end a run of three straight silvers in the event for Kenya.
GB’s Alyson Dixon and Sonia Samuels finished 28th and 30th respectively.
Sumgong, who fell on her way to victory in London this year, and Kirwa pulled away from Dibaba in the final 2km in humid conditions in Rio.
Kenya-born Kirwa, who secured Bahrain’s first ever Olympic silver and second medal of all time, failed to stay with Sumgong and both women looked physically exhausted after they crossed the line.
“I was never worried that I’d lose this,” said Sumgong.
“At 40km I knew the gold was mine. At 35km I noticed that my other two team-mates had dropped off and that gave me the motivation to carry on.
“At 40km I saw there were three of us but I knew whatever happened I couldn’t lose the gold and then I knew I was on the way to history.”
Women’s marathon world record holder Paula Radcliffe
“The conditions will have taken their toll. The way Sumgong stumbled over the line shows that.
“It was a race of attrition and about who could hold and leave enough. Sumgong dominated that race mentally as well as physically.”