EUGENE — Before he kneeled into the starting blocks, LaShawn Merritt tugged on his new necklace — the red-white-and-blue one his friend gave him before the race.

When it was over, after he beat the once-invincible Jeremy Wariner for the second time in five weeks, Merritt looked like a good candidate to have some gold dangling from that neck in Beijing next month.

Merritt proved once again Thursday that the men’s 400 meters is anything but a foregone conclusion this summer, defeating the defending Olympic champion at the U.S. track trials to set up a big Olympic rematch.

“My whole motto is, ‘If I didn’t think I could win, I shouldn’t train as hard as I do,’” Merritt said. “Point blank, nobody trains hard to be No. 2 in the world. If you’re racing and get second place, you go back and train harder to be No. 1.”

Merritt didn’t think it was an upset. And Wariner still did enough to earn his spot on the Olympic team in his best event.

“I made the team, now my next goal is to win the Olympics,” Wariner said. “It’s going to motivate me to work harder. The trials is one thing, the games is the bigger one.”

Merritt finished in 44 seconds flat, defeating Wariner by 0.20 and leaving Wariner still as the only person to crack 44 seconds this year (43.98).

Earning the third Olympic spot was national indoor champion David Neville.

Moments before, the women’s 400 went as expected, with Sanya Richards winning and Mary Wineberg and Dee Dee Trotter capturing the other two spots.

In the 1,500-meter quarterfinals, Bernard Lagat, Lopez Lomong, Alan Webb and Leo Manzano advanced to today’s semis. Lagat, already qualified for the Olympics in the 5,000, finished fourth in his heat, clearly saving energy for two more races to come.

In the women’s steeplechase, Anna Willard set an American record, finishing the 3,000-meter race in 9 minutes, 27.59 seconds. She bested Lisa Galaviz’s record of 9:28.75, set last year.

Lindsey Anderson and Jennifer Berringer finished second and third to earn spots on the Olympic team.

The race of the night, however, was the men’s 400.

Wariner took to the track in his trademark sunglasses, and Merritt wore the necklace his massage therapist made for him.

“The red, white and blue is about making the team,” Merritt said. “I crossed the line, got on the podium and got on the team.”

Starting in lane 6, one lane outside Wariner, Merritt jumped to a slim lead about halfway through, though that’s nothing surprising; Wariner does his best work in the final 150 meters.

But Merritt did not let up, and as they started down the backstretch, it became clear Wariner would not make a move to catch Merritt, who finished second to Wariner at the world championships last year.

“LaShawn was the better man tonight,” Wariner said.

When it was over, Merritt raised both hands in the air. Victories like this don’t come often.

Wariner, meanwhile, isn’t used to losing, but he has lost two of the last three races with Merritt in the field. Merritt snapped Wariner’s nine-race winning streak in June in Berlin, a result that turned heads simply because nobody has really challenged Wariner since he won the Olympic gold four years ago. Merritt is now 3-12 lifetime in races against Wariner.

Both of Wariner’s losses have come since he parted ways with his former coach, Clyde Hart. Those in the inside-track scene almost certainly will analyze that one for a while.

“We knew all along he was the better 200-meter runner than Jeremy,” Hart said of Merritt. “And now that he has gotten his finishing kick, it’s going to be interesting.”

Brittney Reese, Grace Upshaw and Funmi Jimoh qualified for the Olympic team in the long jump. Reese won with a personal best jump of 22 feet, 93⁄4 inches, the best by an American this year.

Upshaw added this Olympic trip to her 2007 national outdoor championship. Jimoh earned her spot a month after being the best American jumper here at Hayward Field in the Prefontaine Classic.