Lagat won his heat in 13 minutes, 39.70 seconds to move on to Saturday night's medal race. He didn't qualify for the 1,500-meter final, adding his name to a list of high-profile American flame-outs at the Bird's Nest.
The U.S. team entered Wednesday with only three gold medals, and two of them came from the most unlikely of sources — discus thrower Stephanie Brown Trafton and 100-meter hurdler Dawn Harper.
Meanwhile, Lagat, Tyson Gay, Sanya Richards, Lolo Jones and Reese Hoffa have all been disappointments. Of the five gold-medal contenders, only Richards got anything — a bronze after she blew a big lead in the 400-meter final.
Lagat, who won silver and bronze medals for his native Kenya in the 1,500 at the last two Olympics, was hoping to double in the 1,500 and 5,000 for the U.S.
He became an American citizen in 2004 and at last year's world championships — his first major international competition for the United States — he won both races.
In the 5,000 on Wednesday, he was among the top four entering the final lap and used a strong finishing kick to pass everyone.
In the first of three heats, American Matt Tegenkamp sliced through the lead pack in the final straightaway to win in 13:37.36 seconds.
In the men's 800, where the U.S. is not considered a medal threat, Nick Symmonds advanced past the first round while Andrew Wheating and Christian Smith failed to make it out.
Smith is the runner who memorably dove across the finish line at the U.S. Olympic trials to earn the third and final spot in Beijing.
He said he knew he'd need to run a personal best simply to advance at this level, but his time of 1:48.20 was 3 seconds off that and nowhere close to what he needed to earn a wild-card spot.
The top two runners in each heat automatically advanced, but Smith was more than a body length out of second place and said diving was not an option.
"I can't even compare it to any football fields I've been to," Smith said of the Bird's Nest. "I wanted so badly to get to the next round, but the race was slow. I felt all right, but couldn't close with those guys."
