American Justin Gatlin roared to a 100 metres victory in Japan on Sunday, as track and field's pantomime villain kicked off his preparations for this summer's Rio Olympics.

Floored by Jamaican sprint king Usain Bolt in the 100m and 200m at last year's world championships, two-time doping offender Gatlin clocked a time of 10.02 seconds into a slight head-wind in Kawasaki in his first test of the season.

"Definitely it's given me motivation, but also it's made me smarter and wiser," Gatlin told AFP, referring to his Beijing disappointment.

"Usually you can come with a strategy that can combat the whole field," added the 34-year-old after finishing well clear of Japan's Ryota Yamagata (10.21) and Ramon Gittens of Barbados (10.26), despite a sore right ankle.

"But when you go against someone like Usain, who is unique in stature and talent, you've got to come with a contingency plan, a plan B."

Gatlin had been unbeaten in 28 races over two years before Bolt's ruthless Beijing take-down of his American rival, whose frustration at being demonised in the media was plain to see.

"It has made me a smarter and wiser competitor to know when to stay within my technique, execute my race and just worry about myself," said Gatlin, who runs in Shanghai next week.

"I rolled my ankle in November -- it was almost a break. It's still swollen so to be able to come out here and run this race, just smooth, I'm happy with that."

Local favourite Yoshihide Kiryu, who has run a wind-assisted 9.87, finished fourth in 10.27, just ahead of Japanese schoolboy sensation Abdul Hakim Sani Brown, the 17-year-old who broke Bolt's meet record in the 200m at last year's world youth championships.

Former 400m Olympic champion Jeremy Wariner trailed home third behind Jamaican-born teenager Julian Walsh of Japan, who won in a personal best of 45.68 with Jarrin Solomon of Trinidad and Tobago (45.77).

Wariner, hoping to make the United States team for Rio his country's Olympic trials in July, faded badly in the home straight to finish in 46.04.

"No excuses," the 2004 Athens gold medallist and twice world champion told AFP. "It wasn't what I wanted. My (first) 200 was good but I think the wind got to me down the home stretch.

"It is what it is," added Wariner, who took silver at the 2008 Beijing Olympics before a torn hamstring sabotaged his bid in London four years ago. "I've got some work to do."

World champion Tianna Bartoletta won the women's long jump with a best leap of 6.61 metres, the American edging out Australian Brooke Stratton (6.55m) and China's Xu Xiaolang (6.47m).

Canada's Shawn Barber, who captured pole vault gold in Beijing, claimed top spot in Kawasaki after clearing 5.62 metres.

Asian champion Xie Wenjun led a Chinese double in the 110m hurdles, clocking 13.36 seconds with Zhang Honglin runner-up in 13.59 and Japan's Hideki Omuro third in 13.61.