Finland's Mira Potkonen on Monday sprang the first major upset of the Rio Games women's boxing when she defeated Ireland's Olympic champion Katie Taylor.

Potkonen was the vast underdog in their lightweight quarterfinal but Taylor, who made history at the London Games in 2012 when women's Olympic boxing made its debut, struggled to find her rhythm despite loud support from Ireland's colourful travelling fans.

The Finn burst into tears when she was awarded the bout on a stunning split-points decision, as the Irish fans looked on in horror.