Aaron Peirsol takes advantage of an opening

Ryan Lochte stepped aside and Aaron Peirsol took full advantage of the backstroke lifeline.

Peirsol had been on the outside looking in after the morning heats Wednesday at the Pan Pacific Championships in Irvine. But he got a second chance when Lochte scratched from the 100-meter backstroke final.

He didn’t mess up, or miss, this time.

The Orange County-reared Peirsol won the event in 53.31 seconds (a meet record) by getting out fast and holding off a determined charge from Junya Koga of Japan, who was second in 53.63.

“I should start off by thanking Ryan Lochte,” Peirsol said. “I owe him ... something after the meet.”

Later, in the mixed zone, Peirsol thought about what he was going to do for Lochte, and suggested that he would buy him a beer.

What put Peirsol in an unusual position was the strength of the American team. The format of this meet is that only two swimmers from a country can move on to the finals at night.

And Peirsol was the third-fastest American in the morning heats. Lochte, to his credit, didn’t keep him in suspense for long and opted to concentrate on the 200 freestyle, which he ended up winning in 1:45.30.

“After this morning, how bad it hurt, I definitely did not want to swim it again,” Lochte said. “I was really tired this morning.”

Lochte and Peirsol chatted about it on the bus ride after the preliminary session.

“He was like, ‘I think I’ve got to say thank you,’ ” Lochte said. “I was like, ‘Just promise me this, that’ll you’ll whoop up on everyone.’

“He was like, ‘All right. Whatever happens, this one is for you.’ ”

Said Peirsol: “So I wanted to make the most of the opportunity. It was very altruistic of him. He didn’t have to do that for me.”

Peirsol, who holds the world record in the 100 backstroke, had a funny line, or two, about the event, which has occasionally been a problem for him in the morning heats.

“No one will leave me alone in that race,” Peirsol said, smiling, adding he still loved it. “It’s me trying to fend off 20 people instead of three.”

Not quite like that for Michael Phelps in his signature races. But he’s dealing with his own physical issues. He won the 200 butterfly in 1:54.11 and Nick D’Arcy of Australia was second in 1:54.73.

Still, Phelps was not thrilled and clearly feeling the hurt.

“It was painful, oh my … I wanted to go 1:53,” Phelps said in his interview on the pool deck. “There were some things I didn’t do well in that race that could have been the difference.

“I think I chopped a couple of walls ... small technical things.”

Phelps, who has not lost in the 200 butterfly in eight years and has a winning streak at 31 in a row in the event, drew a laugh from the crowd when asked how close he was to where he wanted to be.

“A long way, a long way,” he said.

Among the other winners on Day 1: Jessicah Schipper of Australia in the 200 butterfly, Allison Schmitt in the 200 freestyle, Emily Seebohm of Australia in the 100 backstroke, Kate Ziegler in the 800 freestyle, Ryan Cochrane of Canada in the 1,500 freestyle and Cesar Cielo of Brazil in the 50 butterfly.

lisa.dillman@latimes.com

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