Former Olympic gold-medallist Justin Gatlin and world champion Carmelita Jeter ramped up their preparations for London 2012 when they led a US sprint clean sweep in South Korea on Wednesday.
Gatlin grabbed the men's 100m at 9.93sec and Jeter won the women's 100m with 11.11 as American runners snatched all five sprint titles at the World Challenge meeting in Daegu.
Gatlin, 30, has hit scintillating form as he bids to recover from a four-year doping ban by reclaiming the 100m Olympic title he won at Athens in 2004.
Fresh from an impressive victory at the Diamond League opener in Doha last week, the 30-year-old was the only sprinter to break 10 seconds at the venue which hosted last year's world championships.
Compatriot Mike Rodgers was second at 10.06, and Jacques Harvey of Jamaica was third at 10.16.
In the men's 110m hurdles, Aries Merritt led an American one-two-three at 13.21, with US record holder David Oliver and world champion Jason Richardson taking second and third.
Jeter led the American charge on the women's side. Though her winning time was well off her world-leading 10.81 set earlier this month, she remains unbeaten in 10 consecutive finals and hasn't lost a 100m race for a year.
Dawn Harper was another American sprint champion, capturing the women's 100m hurdles at 12.65, beating compatriot Kellie Wells by one-hundredth of a second.
The women's 200m also had a one-two finish by the Americans, with LaShauntea Moore winning at 22.71 and ChaRonda Williams in second at 22.82.
Sherone Simpson of Jamaica was disqualified for a false start.
In the men's 400m, Kirani James of Grenada finished first in 44.72 sec, a meet record, on the same track where he upset Olympic champion LaShawn Merritt for the world title last year.
Mohammed Aman of Ethiopia, the world indoor champion this year, also set a new meet standard of 1:43.51 in the men's 800m. Kenya's Leonardo Kirwa Kosencha was second and Denmark's Andreas Bube was third.
Kenya's Eunice Jepkoech Sum topped the women's 1500m race at 4:05.99, edging Ethiopian Meskerem Assefa, who came in at 4:06.52.