David Plummer upset Peirsol, the "Backstroke King" and world-record holder in the event. Plummer pulled it off in comeback fashion, clocking in at 53.60 seconds, barely ahead of Peirsol's 53.63, to claim his first national title.
When it ended, Plummer climbed out of the pool and two ladies greeted him after he talked to the crowd. The 24-year-old earned an automatic spot on the USA Swimming Pan Pacific Championship team.
"It makes you think I can be the best in the world one day," said Plummer, the former University of Minnesota swimmer who competes for Minnetonka Swim Club. "You can do it from anywhere. You don't have to train next to the best in the world to be the best in the world."
Plummer can now put his name next to Peirsol. There was no mention of a Plummer in the contenders to follow in the event.
Peirsol noticed Plummer when he never went away down the stretch.
"I actually thought I was going to try to get him at the finish," Peirsol said. "My finish was a little short. I thought I had a good finish."
Peirsol is not finished at nationals. He has the 100 butterfly today and the 200 backstroke on Saturday.
Salo will be back as well to watch Peirsol and make sure everything runs smoothly behind the scenes at nationals. He said the first two days have kept him and his hundreds of volunteers busy.
Three days remain before Novaquatics gets ready for the next events at the William Woollett Jr. Aquatics Center. The Junior National Championships are on Aug. 9-13, followed by the Pan Pacific Championships on Aug. 18-22.
"Irvine is a great host city for an event like this," Salo said. "I think a lot of the athletes like the outdoor venues and there [are] not a lot of places you can do that reliably. The air quality is always good.
"We have added stands in the south end [to give us the capacity to hold 6,000 fans]."
Fans on opening day saw dancers perform in between races, something new for swimming. Salo said the dancers, who danced on a stage behind the starting blocks, were not his idea.
"USA swimming has really done a good job learning how to make it more than just a swim meet," Salo said. "They want to have entertainment going on and make it interesting. It really makes it a full week of entertainment."