RIO DE JANEIRO (AFP) - Monica Puig won Puerto Rico's first ever Olympic gold medal on Saturday when she defeated Germany's Angelique Kerber 6-4, 4-6, 6-1 in the women's tennis singles final.

The 22-year-old Florida-based Puig defied her ranking of world No. 34 to get the better of the world No. 2 and Australian Open champion on the back of a sizzling 54 winners.

Puig, who also knocked out French Open champion Garbine Muguruza in the quarter-finals, is the first woman from the Caribbean island to win a medal of any sort. Before her golden breakthrough, Puerto Rico had won just eight Olympic medals, two silver and six bronze. Six of that total had come in boxing.

Victory for Puig came in a dramatic seventh game of the final set when she saved six break points before taking gold on a fourth match point when a Kerber forehand sailed wide.

"Oh my God," she screamed before breaking down in floods of tears and parading her national flag around centre court.

Kerber had cruised into the final without dropping a set as the second seed aimed to emulate Steffi Graf who was Germany's last champion at the 1988.

However, her perfect record in Rio ended when Puig grabbed the first set against a suddenly lacklustre looking German who required treatment on a back injury between sets.

"She deserved to win," said Kerber, a Wimbledon finalist last month. "It's not the medal I wanted but it's still a silver. She was hitting everything, she played a great match.

"It's still a special feeling. I am having the best year of my career."

Two-time Wimbledon champion Petra Kvitova won the bronze medal play-off by defeating American seventh seed Madison Keys 7-5, 2-6, 6-2.