Christian Coleman, bothered by a right leg injury, eased up before finishing fourth in a 100m in Rome on Thursday. Countryman Ronnie Baker beat Coleman for the second time in a week.
Baker, a 24-year-old who has not made an Olympic or world outdoor championships team, clocked a personal-best 9.93 seconds into a slight headwind, the fastest wind-legal time in the world since August.
Coleman, who finished between Justin Gatlin and Usain Bolt at the 2017 Worlds and ran faster than the indoor 60m world record three times in the winter, crossed in 10.