Elaine Thompson of Jamaica celebrates winning. [Photo/Agencies]

A changing of the guard in women's sprints doesn't mean a redrawing of the map.

The 100m Olympic gold medal is heading back to Jamaica, only this time in the hands of Elaine Thompson, the 24-year-old who took down the USA's best, to say nothing of her training partner, two-time defending champion Shelly-Ann Fraser-Pryce.

Thompson turned what was supposed to be one of the most competitive races on the Olympic program into a runaway on Saturday.

Running even at the halfway mark with Fraser-Pryce and Tori Bowie of the United States, Thompson pulled away over the last half and defeated Bowie with a sizeable slice of daylight in between.

Thompson finished in 10.71 seconds, a full .12 better than Bowie and only .01 off the time she ran to beat Fraser-Pryce at Jamaica's national championships last month.

Thompson's 10.70 in Kingston was the best of five sub-10.8 women's sprints this year and served notice that things could be changing once the sprinters reached Rio.

"Jamaica has so many talented sprinters," Thompson said. "To be the second champion, I'm really happy."

Three of those sub-10.8 women were in the final－Bowie and another American, English Gardner, were the others－as was Fraser-Pryce, the 29-year-old who was a newcomer when she won her first of two golds at the Bird's Nest in Beijing eight years ago.

The evening's best drama came earlier in the men's 10,000 meters, where Britain's Mo Farah defended his title, rallying after he tripped and fell with 15 laps to go.

Day 2 closed with Jessica Ennis-Hill coming up 35 points short of defending her title in the heptathlon.

In between, US long jumper Jeff Henderson leapt 8.38 meters to overtake Luvo Manyonga of South Africa to claim gold on his last jump.