Jeremy Wariner

After their respective first-round heats on Monday, Merritt declared "it's time to show down and throw down." Wariner exuded quiet confidence about his quest to join Johnson as the only Olympic 400-meter back-to-back champions in 112 years.

"I knew Jeremy was always going to bring his A-game," Merritt said. "I just had to bring my A-plus game. I did that today. Today, I was just the better man."

But the reality is that Wariner was at best a C, which few would have predicted after watching him breeze through the first round and semifinals.

Although Merritt defeated Wariner at last month's U.S. trials, Wariner had won two subsequent match-ups and owned a 14-3 record in races both men started and finished.

"I'm disappointed," Wariner said. "If I would have run like I did in the semifinal, I think I would have won. . . . LaShawn just ran a better race today and I can't say nothing about that."

If the often frosty rivals were evenly matched coming in, the lane assignments might have tilted the scales toward Merritt. From lane 4, Merritt could easily track Wariner's progress out in lane 7.

Wariner, staggered in front of and to the right of Merritt, most likely would not see his adversary until after the final turn. In fact, Wariner said he "didn't see" Merritt at all as he zoomed past on the inside.

At that moment, Wariner was too busy wondering why his legs wouldn't respond. He said it was not a case of going out too fast and running out of gas.

"Not at all," he said. "I ran exactly how I wanted to."

Merritt's winning time was a personal best, though slower than Wariner's career mark of 43.45 set at last year's World Championships in Osaka. Merritt took silver that day, and has remained in No. 1-ranked Wariner's shadow for most of the last four years.

Despite his pre-race bluster, Merritt was stunned by what he saw when he glanced out of his right eye with 15 meters left.

"I knew I had the race when I was coming down the home stretch and I actually looked over and didn't see anybody," Merritt said. "Actually, I looked over and saw a pole or something. I thought it was somebody else, but it wasn't him."

As Wariner labored across the finish line, David Neville dived past the Bahamas' Christopher Brown, giving America its second straight men's 400 Olympic medal sweep.

In Athens four years ago, it was 20-year-old Baylor junior Wariner leading the way. With the 4x400 relay this weekend, he still has an excellent chance to win his third gold in the last two Olympics.

"I've got to look past this," he said. "I can't let it affect the way I run the rest of this year and in my future."

His long-stated goal is to compete through 2016. Given their ages, Wariner and Merritt could jostle at the top the entire time. But no matter their head-to-head outcomes, Merritt for the next four years will be the reigning Olympic champion.