Monica Puig beat Angelique Kerber in three sets in the women's singles final to win Puerto Rico's first ever Olympic gold medal.
Unseeded Puig, 22, beat the German world number two 6-4 4-6 6-1.
Reigning Australian Open champion Kerber, 28, simply could not match the intensity of her younger opponent in the deciding set.
Earlier, Petra Kvitova of Czech Republic beat USA's Madison Keys in three sets 7-5 2-6 6-2 to win bronze.
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