RIO DE JANEIRO (AP) — Dutch coach Bart Bennema sighed and assessed his star pupil.

"She has become a sprinter now," he said.

What? Dafne Schippers, a sprinter only "now" in 2016, a year after she won gold over 200 and silver over 100 meters in Beijing to become the dominating sprinter of the last world championships ahead of the Olympics?

It just shows what the U.S. and Jamaican sprinters will have to deal with — an orange streak of speed running from her heptathlon past and perhaps toward Olympic fame.

The women's 100 begins Friday on the opening day of track and field. If all goes according to plan, the Dutchwoman will be competing for seven days before the closing weekend — adding the 200 and relays as well — and end up with several medals, several possibly gold.

The key will be her start — erratic when she still was a heptathlete up to last year, and rapidly improving as she prepped for the Rio Games.

"The faster my start, the better the rest of the race will likely be," she said leading to Friday's first race. But she will be running against rivals who have focused on those critical first meters since they began sprinting as youngsters while Schippers was still working on her javelin, high jump, shot put and hurdles skills.

All too often, her reaction to the gun was slow. She would get fully upright too soon, losing early momentum and facing the full force of air against her body.

Increasingly this season, at 24, she gets out with the best, and has developed the gliding, slowly rising movement that delivers her with perfect speed to the midpoint of the race.

"It does look better, no?" Bennema said in an interview with The Associated Press after last month's European championships.

The trick? Recently, she has been training with the Dutch male sprinters, including European champion Churandy Martina.

"Who better to start with than the men and see how close I can stay at 10, 20 or 30 meters," Schippers said. "I'm still up there at 10, but see them running away a bit as off 20."

"It feels right, I feel steady. And this is what counts. Step by step, and this gives me confidence," she said. Especially since no one has questioned her ability and speed once she is in full flow.

Such improvement is a major reason why Bennema has elevated Schippers to a true sprinter.

For Schippers, there are other reasons, too. She loved the heptathlon, where athletes compete in seven events over two days, but it was an exceptional wear on both body and mind.

Ankles would hurt from the jumps, shoulders from the throwing, all a drain on the sprints where she could really excel. What long kept her from making the move to sprinting was the fun of the mix and her sheer raw talent for multi-events. After all, she won bronze at the 2013 worlds. It was worth the pain.

"The pains of a heptathlete have gone, but now I have new pains of the sprint," Schippers said, pointing to the hamstrings and hips. "Sprinter worries," she calls them.

Mentally though, the advantages are clear. If it wasn't the problem of a perfect release of the javelin, it was how to get the best extension for the shot put.

"I used to feel I always was a bit behind, and now on I can work so hard on just one thing," she said. It will be tough enough though.

Since her gold in Beijing, few would argue against her being the best 200 runner of the moment, especially since Allyson Felix failed to even make the U.S. team. Schippers has four of the top six times this year.

The 100 is more daunting. She has only the eighth best time of the season, though she did race into a wind in most of her races. Americans Tori Bowie and English Gardner and double defending champion Shelly-Ann Fraser-Pryce of Jamaica are among the favorites.

Schippers is undaunted, and her full conversion to sprinter has given her something precious.

"To focus on one thing is something completely different than concentration on seven," she said. "In my mind, I have this peace now."

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Follow Raf Casert on Twitter at http://twitter.com/rcasert