Justin Gatlin booked his place at the IAAF World Cup in Athens after taking the 100m title at the US Championships in Indianapolis on Friday.
Gatlin had clocked 9.99secs for the 100m earlier in the day
The Olympic champion claimed victory in a time of 9.93 seconds to finish ahead of Tyson Gay and Shawn Crawford.
Marion Jones also sealed a place in Team USA for the September meeting after winning the women's 100m by just 0.07 seconds in a time of 11.10.
World champion Lauryn Williams was second with Torri Edwards in third.
Both events were disrupted after the weather caused the postponement of the heats, with Gatlin and Jones forced to run three times in one day.
"I'm happy to get the win - a win is a win," said Gatlin, who equalled the world record time of 9.77sec in Doha last month.
"I wanted to come out here and put on a show for the fans. Running three rounds was a big factor and maybe why I wasn't able to produce a great time."
Jones, still trying to put behind her the doping allegations arising from the Balco doping scandal, was delighted to have claimed her first sprint title since 2002.
"It is a satisfying feeling," she said. "It feels great. It was a challenging three rounds and experience plays a big part in it.
"I've had the highest of the ups and the lowest of the lows I definitely feel I am on my way back."