Zagreb - World silver medallist Justin Gatlin of the United States was out-trumped by compatriot Mike Rodgers in the 100m at the World Challenge meet in Croatia on Tuesday.
Rodgers, who won silver in last month's world championships alongside Gatlin in the 4x100m relay, clocked 9.97sec.
Jamaican Kemar Bailey-Cole, a training partner of Usain Bolt and Yohan Blake, came in second in 9.99sec, with Gatlin in third (10.01).
The American now faces a run-out against Bolt, who won treble gold in Moscow, at the Brussels meet of the Diamond League on Friday.
In a top-notch field in the men's 110m hurdles, American David Oliver secured the win to continue his world gold medal form in 13.25sec, ahead of teammate Ryan Wilson, with Cuba's 2008 Olympic champion and former world record holder Dayron Robles in third.
Reigning Olympic champion Dawn Harper won the 100m hurdles in 12.63sec ahead of Australia's Sally Pearson (12.75), who won silver in Moscow behind Brianna Rollins.
The women's 800m saw a rare outing for Caster Semenya, but the South African could only finish fifth in a race won by Ekaterina Poistogova in 1:59.03.