Galen Rupp beat Bernard Lagat to win the 5,000m race and secure the first men's long distance double at the US Olympic trials for 60 years.
The 26-year-old had already won the 10,000m at the trials and a late surge saw him pass former world champion Lagat to clinch victory.
Rupp, a good friend and training partner of Britain's Mo Farah, clocked 13 minutes 22.67 seconds.
Lopez Lomong finished third with a time of 13:24.47.
The top three all secure their places in the 5,000m at London 2012, where they will compete against reigning world champion and gold medal favourite Farah.
Farah, 29, left Britain 18 months ago to train in America with Rupp, and the two have developed a strong friendship - one that Rupp insists will not be made awkward when they compete against each other in London.
"I look at it as a great opportunity," he said. "We're both going [to London] to be up there for the medals. Afterwards, we're still going to be friends.
"He's like a big brother mentoring me. He's just the most humble, quality, hardworking guy there is."
Other winners at the trials included US record holder Brad Walker, with a clearance of 5.67m in the pole vault, and Lance Brooks, who threw 65.15m in the men's discus.
Long jumper turned sprinter Tianna Madison recorded the day's fastest time as qualifying began in women's 200m.
The 2005 world long jump champion clocked 22.57 seconds to win her heat as she bids to make the USA team for London in a second event after finishing second in the 100m earlier in the trials.
World 100m champion Carmelita Jeter, Sanya Richards-Ross, Allyson Felix and Jeneba Tarmoh also advanced.
Christian Taylor topped qualifying in the men's triple jump as the current world champion recorded 17.27m on his only attempt.
Olympic silver medallist Kerron Clement led qualifying in the 400 hurdles with a run of 49.37 seconds, with Olympic champion Angelo Taylor second fastest at 49.53.
The trials continue through to Sunday with the top three finishers in each event booking their place at London 2012, provided they have met the Olympics qualifying standard.