Allyson Felix and Justin Gatlin produced differing results in their Diamond League season debuts in Shanghai on Sunday.
Felix finished fifth in a 400m race, her first competition since tearing her hamstring in the 200m final at the 2013 World Championships on Aug. 16.
Felix, the most decorated U.S. female track and field athlete with six Olympic medals and 10 World Championships medals, ran one lap in 50.81 seconds, a half-second behind winner Novlene Williams-Mills.
Felix has said she is focusing more on the 400m this year as a complementary event to her 200m specialty. Last May, she ran a 400m in 50.19. In 2011, when she also put emphasis on the 400m, Felix recorded her personal best of 49.59 in winning a world silver.
In the 100m, Gatlin posted a world-leading 9.92 seconds, dominating after 30 meters and dusting the field by two tenths with zero wind.
“I have much more left in the tank,” Gatlin said, according to The Associated Press. “I cruised at 9.92 with no wind. I felt I made it look easy.”
World bronze medalist Nesta Carter was second in 10.12, followed by American Mike Rodgers in 10.18.
Jamaican stars Usain Bolt and Yohan Blake have yet to debut at 100m this season but will chase Gatlin’s mark in races over the next month.
The Diamond League next moves to Eugene, Ore., for the Prefontaine Classic on May 31.
In other results Sunday, Nigerian Blessing Okagbare won the long jump and the 200m, two events she earned medals in last year’s World Championships.
In the 200m, Okagbare crossed first in 22.36 seconds. Jamaican world champion Shelly-Ann Fraser-Pryce pulled out of the meet with a reported shin injury, and two-time Olympic champion Veronica Campbell-Brown faded to fifth in 23.08.
Olympic champion and world record holder Renaud Lavillenie won the pole vault with a top clearance of 5.92 meters.
China’s Xie Wenjun shocked the 110m hurdles field to win in a personal best 13.23. Xie defeated all three 2013 World Championships medalists and the 2008 Olympic champion, with 2004 Olympic champion and Chinese superstar Liu Xiang smiling in the stands.
World champion David Oliver was third in 13.28. Beijing Olympic champion Dayron Robles was sixth in 13.48.
Beijing Olympic silver medalist Christian Cantwell continued his spectacular early season shot put form with a winning 21.73m throw. Cantwell, who missed much of last season due to injury, has four of the top six throws this year.
Olympic and world silver medalist Michael Tinsley emerged after the final hurdle to win the 400m hurdles in 48.77. World champion Jehue Gordon was sixth in 49.56.
Abeba Aregawi pulled away to beat American Jenny Simpson in a battle of the last two world 1500m champions. The Swede Aregawi clocked 3:58.72 and became the first woman under four minutes this year.
Emma Coburn notched a rare American 3000m steeplechase victory in 9:19.80, beating a field that included all three 2013 World Championships medalists by 5.96 seconds.