Going shoulder to shoulder in the 400-meter semifinals Monday night at U.S. Olympic trials, Wariner beat Merritt by .10 seconds to set up a rematch in the finals Thursday.
Wariner, the defending Olympic champion, improved to 12-2 lifetime against the man who figures to be his biggest competition this summer, finishing in 44.66 seconds and setting aside a loss to Merritt in Berlin last month that shook up the sport a bit.
"I think all Merritt and me were trying to do was just qualify, and make sure we get a preferred lane," Wariner said. "We both qualified 1-2, so it's going to be interesting to see how the lineup is come Thursday. But we'll be ready."
In the decathlon, Bryan Clay made his second straight Olympics with a personal-record score of 8,832. That marked the best score by an American in 16 years and bested Dan O'Brien's Olympic trials record.
While Clay can relax now, Wariner and Merritt still have work to do.
It figures to be a two-man show when they meet Thursday in the finals, though you didn't have to work hard to see them go at it on this night, either -- even though the air was thick with haze and smoke due to winds blowing northward from the forest fires in California.
Wariner was in lane 4, Merritt in lane 5, and Merritt had a lead on the backstretch. But at about the 250-meter mark, Wariner started reeling him in. He had a comfortable lead down the stretch and, though Merritt closed the gap at the very end, it wasn't by enough.
Merritt said that, like Wariner, his top priority was to make the final. Asked if he wanted Wariner next to him again Thursday, when the top three finishers get trips to the Olympics, he said "lanes do make a difference."
"They shouldn't, but come Thursday, all you've got to do is run your race. No matter what lane you're in, if you run your race, you'll be all right," Merritt said.
Wariner has said he thinks he has a good shot at Michael Johnson's venerable world record of 43.18 seconds at some point this summer, and Johnson said Saturday he thinks Wariner might be better off with someone pushing him.
Merritt appears to be the guy, though his win last month was somewhat unexpected. The only other time Wariner hadn't beaten him head-to-head was when he pulled up and did not finish. This was their first rematch.
"It didn't startle me," Wariner said in an interview Saturday. "There have been races in the past where LaShawn has been with me at the 300 mark. The difference was, in those races, my finish was stronger. In Berlin, when I tried to kick for my finish, I didn't go" anywhere.
In the women's 400, Sanya Richards advanced easily out of the semifinals, keeping her Olympic hopes alive after missing the world championship squad last summer because of illness.
Richards is taking medicine to treat a disease that causes lesions in her mouth, and has been told by doctors to keep her stress level low to prevent flare-ups.
That was no problem on this night. She sprinted to a huge lead and pretty much jogged the last 50 meters but still finished in 50.75 seconds to make it to Thursday's finals.
"I thought if I would've pushed that one in, I might've been 49-low," Richards said. "I felt really strong. I'm going to save that run for Thursday. Hopefully the time will come."