By Mitch Phillips

RIO DE JANEIRO (Reuters) - Elaine Thompson maintained Jamaica's incredible stranglehold on Olympic sprinting on Wednesday when she added the 200 meters gold to the 100m title she collected earlier at the Rio Games, while Usain Bolt remains on course for a track 'triple-triple'.

After winning nine of the 12 sprint events in 2008 and 2012 combined, Jamaica have now won the first three in Rio and, with Bolt impressively advancing to the 200m final and their relay teams oozing talent, they could take all six.

While the days of the United States dominating sprinting are long gone, they can at least take some consolation from their own special sweep on Wednesday.

Brianna Rollins, Nia Ali and Kristi Castlin completed an unprecedented 1-2-3 in the 100m hurdles - the first gold on the track at the Rio Games for the United States.

The United States also took gold and silver in a fantastic long jump final through Tianna Bartoletta and Brittney Reese.

While Bolt is now one step away from securing a third Olympic sprint double, he had to give top billing on Wednesday to compatriot Thompson, who delivered gold in the 200 despite nursing a tight hamstring.

Thompson faced stiff opposition, particularly in the shape of Dafne Schippers, but after running a terrific bend she maintained her form to hold off the Dutchwoman and crossed the line in a season-leading 21.78.

Thompson become the first woman to win both the 100 and 200 since American Florence Griffith Joyner in 1988.

Schippers took silver and American Tori Bowie added a bronze to her silver from the 100.

There was no disputing the depth of 100m hurdles talent on the U.S. team, with world record holder Kendra Harrison and 2008 Olympic champion Dawn Harper failing to make the cut, but to take all three medals was more than they could have hoped for.

Rollins was the clear winner in 12.48 though Castlin had a nervous wait before discovering she had sneaked bronze.

In the long jump Bartoletta soared to a personal best 7.17 meters with her fifth jump to take gold, with defending champion Reese leaving it even later with a last-attempt 7.15 to snatch silver ahead of Serbia's Ivana Spanovic.

Darya Klishina, Russia's one-woman athletics team, finished ninth.

LAZY BOLT?

Bolt and Canadian Andre de Grasse set up a 200m showdown after crossing the line laughing together in their semi-final but 100m silver medalist Justin Gatlin missed out.

Bolt clocked 19.78 seconds with De Grasse claiming a Canadian record 19.80.

"He was supposed to slow down," said Bolt, who chastised himself for being lazy. "I said 'What are you doing, it's a semi-final?' But I think he wanted to push me."

Gatlin, who said he was hampered by an ankle injury, looked well placed before easing up and being overhauled by Dutchman Churandy Martina and Panama's Alonso Edward.

While Bolt remains on course for a triple-triple, Briton Mo Farah is ready to have a tilt at the distance double-double, though he had a scare when stumbling 200 meters from the end of his 5,000m semi-final.

Farah recovered from a fall to win the 10,000 earlier this week. His main rivals from East African countries also made it through to Saturday's final.

Kenya's iron grip on the men's 3,000m steeplechase continued as 21-year-old Conseslus Kipruto triumphed in an Olympic record eight minutes 3.28 seconds.

The East African nation has won every edition of the race since 1968 bar the two it missed due to political boycotts in 1976 and 1980.

Evan Jager took silver for the United while double Olympic champion Ezekiel Kemboi finished third but was disqualified for stepping out of his lane. The bronze went instead to France's Mahiedine Mekhissi-Benabbad.

Hot favorite Caster Semenya qualified for the 800m semi-finals with ease and was immediately plunged into a new gender controversy over her reported hyperandrogeny.

Frenchwoman Justine Fedronic, who failed to advance from the heats, said that while she had sympathy for her rival's situation, her high testosterone levels meant it was not a fair fight.

"When you line up against someone like that, you know it's going to be a completely different ball game," Fedronic said.

"I do feel for her. She is just trying to train and compete just like the rest of us so that is really not fair to her. But it is not fair for others too. So I don't know what the solution is."

Olympic and world decathlon champion Ashton Eaton surged into the lead on the first day of the competition in Rio. The world record holder opened up a cushion with a 7.94m long jump and stretched it with a 46-second 400m.

Germany's Kai Kazmirek and Damian Warner of Canada, who posted an Olympic decathlon 100m best of 10.30, lead the chasing pack.

(Editing by Peter Rutherford)