By Drazen Jorgic

RIO DE JANEIRO (Reuters) - Jamaica's Elaine Thompson completed a memorable Olympic sprint double on Wednesday after storming to victory in the women's 200 meters final, blowing away the field with a season's best run of 21.78 seconds.

The 24-year-old 100m champion beat pre-race favorite Dafne Schippers of the Netherlands, who ran her fastest time of the season in the final but had to settle for silver.

Thompson's dominant victory ensured Jamaica maintained its grip on the Games' most prestigious sprinting titles, as well as making her the first women to win the Olympic sprint double since American Florence Griffith Joyner in 1988.

"My school motto was 'let the light shine' and I let my light shine tonight," Thompson told reporters.

"It's a big surprise to me because I have had a hamstring injury. You must overcome these things and tonight I am standing here with a gold. To beat Dafne is a hard run."

Though Thompson surprised herself with victory, she dazzled from the gun and appeared in complete control. A brilliant start helped her surge ahead of the field and after the bend she never looked like relinquishing her lead.

Schippers' second-place finish in 21.88 seconds made her the first woman outside Jamaica or United States to win an Olympic medal over 200m since 2004, but she was still disappointed by the result.

"I haven't made my mind up about what happened. I'm not happy with the silver," Schippers said.

"I came for gold. I was in good form. My times were OK but they were not strong enough. It's heavy to run six races."

Schippers, world 200m champion, picked up a leg muscle injury ahead of the 100m final last week and said she almost pulled out of the Games.

American Tori Bowie, who won a silver medal in the 100m final, grabbed bronze. The second Olympic medal caps a meteoric rise for the former long-jumper who only switched to sprinting in 2014.

"My goal today was to finish as best I could and I'm leaving with another medal. Who couldn't be thankful for that?," she said.

(Editing by Ed Osmond)