IRVINE, Calif. – Michael Phelps beat world-record holder Ian Crocker in the 100-meter butterfly, and newcomer Cullen Jones outsprinted a talented field to win the 50 freestyle in the U.S. Summer Nationals swimming championships Thursday night.

Phelps is 4-for-4 this week, with two days remaining in the meet that decides the U.S. team for the Pan Pacific championships later this month in Victoria, British Columbia.

He earned his 31st career national title, winning in 51.51 seconds. Crocker, a Portland native and Cheverus High star, finished in 51.73 – well off his world mark of 50.40 set last year. Ryan Lochte was third.

“I’m definitely more pleased now than I was the first day,” Phelps said. “I’ve been getting a little bit more excited about my races and maybe that’s the difference. Maybe I wasn’t as excited as I should have been the first day.”

Phelps and Crocker have been the world’s top two swimmers in the 100 fly since 2003, with Crocker losing the gold to Phelps in the 2004 Olympics, but winning at last year’s world championships.

“It definitely keeps it exciting,” Crocker said. “It keeps me working hard every day just to try and hold him off.”

Crocker typically starts fast, but he was slow off the blocks in the lane next to Phelps with 3,126 fans cheering loudly.

“I haven’t been feeling a lot of speed yet,” Crocker said. “I saw Michael out of the corner of my eye coming back. I knew it was going to be tight one way or the other. But I’m still happy with the outcome, and again, Pan Pacs is more important.”

Jones claimed his first major international trip by winning the 50 free in 21.94. Benjamin Wildman-Tobriner was second in 22.16 and Olympian Jason Lezak was third in 22.22.

Two-time Olympic gold medalist Gary Hall Jr. and Olympian Neil Walker tied for fourth in 22.49. Lezak and Walker are 30 and Hall is 31.

“A lot of big names in that heat,” said Jones, this year’s NCAA champion from North Carolina State.

“One of the things my coach said that I need to do is have them gun for me, and that’s pretty much what they’re going to be doing now.”

Hall took two years off after winning gold in Athens. He returned to training a month ago with the goal of swimming at the 2008 Beijing Games, and now Jones is on his radar.

“I’m very impressed with Cullen. He strikes me as extremely intelligent, a good guy,” Hall said. “You can expect a lot more out of him. He’s established himself as one of the best swimmers in the world.”

Hall’s finish won’t get him to Pan Pacs, but it earned him a trip to the 2007 Pan American Games in Brazil.

“It’s a trip to Rio,” he said, grinning.

Also in comeback mode is Megan Jendrick, the 2000 Olympic champion in the 100 breaststroke. Now 22 and married, Jendrick won her signature race in 1:07.54.

“I was on top of the world at the 2000 Olympics and I went through a lot of ups and downs after that, and just to be back up on the top is really exciting,” she said.

American-record holder Jessica Hardy and Olympian Tara Kirk tied for second in 1:07.65.

Olympian Kara Lynn Joyce won the women’s 50 free in 24.97, her first sub-25 second effort ever. Natalie Coughlin was second and Courtney Cashion third.

Katie Hoff won the 400 individual medley in 4:35.82 – fastest in the world this year. Ariana Kukors was second and Olympian Kaitlin Sandeno third.