OMAHA, Neb. — Michael Phelps will get another shot at Mark Spitz's Olympic record in Beijing.

Gary Hall Jr. won't be going to China at all.

Phelps locked up his eight-race schedule by winning the 100-meter butterfly at the U.S. swimming trials Saturday night, powering away on the return lap to easily beat world-record holder Ian Crocker. The winning time was 50.89 seconds, about a half-second slower than Crocker's 3-year-old mark of 50.40.

"This week turned out how I wanted it to," Phelps said. "I'm ready for the challenge that lies ahead of me. At the Olympics, it's going to be harder than it was here. It's a higher level. And you add the relays in there, and it's the Olympic Games. Hopefully, it's something I can be successful at."

Although Phelps had to be content with setting two world records in Omaha, Margaret Hoelzer put her name in the book with a stunning win in the 200 backstroke.

The 25-year-old got a great surge off the wall heading into her third lap, then closed strong to finish in 2:06.09, beating the record of 2:06.39 set by Zimbabwe's Kirsty Coventry in February. It was the ninth world record of the meet.

Fifteen-year-old Elizabeth Beisel, a rising star in American swimming, rallied to take the second Olympic spot in 2:06.92. Hard-luck Hayley McGregory finished third again, matching her finish in the 100 back and costing her a berth on the Beijing team.

Hall, too, was denied and won't get a chance to go for his third straight Olympic gold in the 50 freestyle. The 33-year-old iconoclast came on deck wearing a red, white and blue cape and used his hands as six-shooters, hoping to take down his younger rivals in his only event of the trials.

But Garrett Weber-Gale touched first with an American record of 21.47, while defending world champion Ben Wildman-Tobriner took the second Olympic spot in 21.65.

Cullen Jones, who set the previous U.S. mark of 21.59 in Friday's preliminaries, was third in 21.81, while Hall settled for fourth in 21.91. He slapped the water in disgust and dunked his head, but had a big smile on his face when he climbed from the water after perhaps the final race of a brilliant career.

"It was a hell of a race," Hall said. "I placed fourth, and it's not an effort that I should be disappointed with. In fact, I'm really proud of it. The future of sprinting in the United States is a bright one, and it'll carry on a long tradition of sprinting that I'm honored to be a part of.

Ever the showman, the 10-time Olympic medalist announced his retirement — sort of.

"This is my last race," Hall said. Then, after a long, dramatic pause, he added, "until I race again."

Weber-Gale, who also won the 100 free at the trials, called it "the best week of my life" but sounded a bit regretful that it came at Hall's expense.

"I'm going to miss Gary and some of his antics," Weber-Gale said.

In the 100 fly, Crocker led at the flip but faded over the final 50. Still, the introspective 25-year-old managed to hang on to a spot on his third Olympic team by finishing second in 51.62.

"How did I feel? Overriding relief," said Crocker, whose largely successful career has been marred by several high-profile flops, including a disqualification in the 100 free prelims here. "I feel like the young wolves were coming out to eat the old one. I'm thankful to get on the team."

Phelps added to his wins in the 200 and 400 individual medleys, 200 freestyle and 200 butterfly. He's also expected to swim all three relays, giving him another shot at Spitz's record of seven gold medals at the 1972 Munich Games. Phelps just missed in 2004, winning six golds and two bronzes.

Katie Hoff, Phelps' former teammate at the North Baltimore Aquatic Club, will be nearly as busy as her pseudo-big brother in Beijing.

The 19-year-old Hoff claimed her fifth individual race of the Olympics with an easy win over defending world champion Kate Ziegler in the 800 freestyle. But Hoff, ever the perfectionist, was about a second off her personal best with a winning time of 8:20.81 and short of the oldest world record on the books — Janet Evans' 19-year-old mark of 8:16.22.

"Going into it, I was definitely planning on it being a really, really tight race," Hoff said. "I would've liked it to be a best time, but I can't be perfect. Maybe this will spur me on to train hard and go for a best time in Beijing."

At the other end of the age spectrum, 41-year-old Dara Torres continued her remarkable comeback, setting a new American record in the 50 freestyle semifinals. The mark fell three times during the day, finally winding up back where it started — in Torres' name when she did one furious lap in 24.38.

She'll have a chance to take it lower in the finals Sunday, the final night of the meet.

Then it's on to Beijing.

For Hall, the journey ended at Omaha. For now.

"Dara's 41," he said. "In 2016, I guess I'll be 41, so maybe I'll be taking some time off for about seven years. That break seemed to work well for Dara."