British distance runner Paula Radcliffe broke the women's world record for 10,000 metres on Sunday, finishing in 30 minutes, 21 seconds to win the World's Best 10,000 road race.
Radcliffe beat the previous record of 30:29, set by Moroccan Asmae Leghzaoui at the New York Road Runner's Club Mini Marathon in June.
The men's 10,000 world record is 27:02, held by Ethiopian Haile Gebrselassie.
"I knew from halfway that I was well under the time (to beat the record)," Radcliffe said.
Leghzaoui came in a distant second at 31:35. Kenya's Esther Kiplagat, America's Lyubov Kremleva and Kenya's Jane Kiptoo rounded out the top five.
Radcliffe will receive a US$100,000 bonus for breaking the world record, organizers said. She also gets US$12,000 from winning.
Radcliffe ran the world's fastest marathon for a woman at 2:17:17.7 last year in Chicago and won gold medals in the Commonwealth Games and European Championships at 10,000 and 5,000 metres.
Nearly half of the San Juan road race takes place on a bridge, which runs over a lagoon and is notorious for strong winds and intense tropical heat.
The race is in its sixth year, but international runners have only been able to compete in the past three.