Canadian Andre De Grasse finished fourth in the men's 100m at the Drake Relays in Des Moines, Iowa, on Saturday in his return from a nine-month injury absence.
De Grasse, whose three medals at the 2016 Rio Olympics included bronze in the 100m, made his first 100m start since July 2017, clocking 10.15sec with a favourable wind of 1.9 metres per second.
American Isiah Young won in 10.02sec, followed by compatriot Mike Rogers (10.03) and Britain's CJ Ujah (10.13).
De Grasse, who took silver in the Rio 200m, suffered a right hamstring injury last summer that forced him out of the 2017 World Championships in London.
He was back in action on Saturday for the first time since winning a 200m in 20.03sec on July 16, 2017 in Rabat.
De Grasse, a 23-year-old touted to emerge as a sprint star in the wake of Usain Bolt's retirement, resumed training in December.
He was targeting a return in time for the Commonwealth Games in Australia in early April, but opted out as a precaution.
"For me, it's all about coming out healthy," he said. "Now there are no limits for my next meet."
World record holder Kendra Harrison ran a wind-aided 12.37 in the 100m hurdles to win her third straight Drake Relays title.
"I'm pleased with it," said Harrison, who added she's next headed to the first Diamond League meeting of 2018 at Doha next week. "I think it's going to set up the rest of my hurdles (season)."
The Canadian Andre De Grasse's last appearance in an international competition was the Diamond League 200m race in Rabat, which he won in 20.03sec