Gatlin, the 2004 Olympic 100 metres champion, was running at the Ergo World challenge meeting in Tallinn as he works towards the London 2012 Olympic Games.
Before August 3, when he also ran in Estonia, he had not raced competitively since June 2006 after being banned because of a positive test for the male sex hormone testosterone and its precursors.
The 28-year-old regained his eligibility to compete in July but he was expected to have difficulty finding races even after the ban ended because of a Euro Meetings recommendation not to invite athletes who bring disrepute to the sport.
Gatlin bettered his final time from the August 3 meeting where he ran 10.24 seconds. His personal best is 9.85. Fellow American Rubin Williams was second on Sunday in 10.25.
"My start is still a little off but obviously my finish is there," Gatlin said.
"I am able to surge and finish good, so once I get my start down better... I have some little muscle aches here and there and will go home and rehab a little, but obviously I can show everybody my times can come down by each race," he added.
His coach agreed.
"He is pushing so hard now out of the blocks, that he is having difficulty controlling it. It is like a car that is starting very fast and fish tailing, but the middle part of the race was quite good and then started galloping at the end rather of sprinting smoothly," sprint coach Loren Seagrave said.
Seagrave added, "there is still room for improvement, the more he runs the more he gets a feel for things."
Seagrave said that Galtin planned to return the United States and will get five or six days of training in, then fly back for the Joensuu meeting in Finland on August 21.
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