Veteran American Kristin Armstrong completed a remarkable Olympic cycling hattrick of gold medals by winning the women's 29.7km time-trial in Rio on Wednesday.

Just a day before she turns 43, Armstrong added to her gold medals from Beijing and London to become the first cyclist to win three Games titles in the same discipline.

In wet and windy conditions, she posted a time of 44min 26.42sec to edge out Russian Olga Zabelinskaya, who only returned from an 18-month doping suspension last year, by 5.55sec, with Olympic road race champion Anna van der Breggen of the Netherlands third at 11.38sec.

Armstrong hit the first time check atop the 1.3km Grumari climb after 10km with a 4.9sec lead over Elisa Longo Borghini of Italy and 6.32sec to Van der Breggen.