Eugene (Oregon) - Tyson Gay powered past teenaged challenger Trayvon Bromell to win the United States 100m crown in 9.87sec on Friday and book his first trip to the World Championships since 2009.
The 32-year-old, who is trying to regain the sport's summit after a one-year drug ban, rated the triumph as perhaps the most important of his career.
"I feel like it was the toughest," he said, noting that rising talents like Bromell were raising the stakes in US sprinting.
He credited his experience with getting him through the rounds with enough left to overhaul Bromell, relegating the 19-year-old to second in 9.96.
"He got out good, it was just one of those 10 years of experience, dig-down moments - I had to get him," Gay said.
"It felt good though."
Mike Rodgers was third in 9.97 to grab the final berth on offer for the Aug 22-30 World Championships in Beijing.
They will join team-mate Justin Gatlin, who has a bye into the 100m in Beijing thanks to his 2014 Diamond League title and is focusing this week on the 200m and a possible double World Championships challenge to Jamaican superstar Usain Bolt.
In Kingston, Jamaica, in the absence of Bolt, whose decision not to run raised fresh concerns about his fitness, former world record-holder Asafa Powell surged to the 100m title at the national trials in 9.84sec.
He pulled away from the field in the last 20m to equal his season best. "I'm still in hard training as we're really focusing on the World Championships so this was just me coming off some hard work and running very fast so I'm feeling very confident," he said.
Nickel Ashmeade leant at the tape to take second in 9.91 while Commonwealth champion Kemar Bailey-Cole was third in 9.97.
Nesta Carter, who won bronze in Moscow, also dipped below 10 seconds with 9.98 but will have to settle for relay duties in Beijing.
Surprisingly, 2011 world champion and 2012 Olympic 100m and 200m silver medallist Yohan Blake failed to make it out of his semi-finals, finishing sixth in 10.36sec.
The results mean the US' punch of Gay and Gatlin will challenge world record-holder Bolt in Beijing.
The Jamaican has been slow to sharpen his edge but Gay is not looking ahead.
"Right now, I'm not paying any attention to Usain Bolt," the American said.
"Everything he does now doesn't really matter because when he shows up at (a) championship, he's always ready."