OMAHA - Most Olympic medalists place their hard-won treasure in a safe-deposit box, or perhaps a special case. Anthony Ervin put his gold medal from the Summer Games up for auction, motivated by a feeling he still struggles to explain.

The California swimmer won it in the 2000 Sydney Games, when he tied with American teammate Gary Hall Jr. for first place in the men's 50-meter freestyle. Four years later, after he had walked away from the sport at age 22, he sold the medal for $17,101 and donated the money to relief efforts for the 2004 tsunami in Indonesia. "I classify myself as somewhat of a mystic at that time,'' said Ervin, 31. "Even with all my vaunted talent, facing that wall of water, I would have died, as well. In order to kind of cleanse myself, I wanted to do something I thought would help, to kind of give myself away.''

Ervin never expected a chance to win another medal. Yet he put himself in position to do so Saturday at the U.S. Olympic trials, swimming the fastest time in the semifinals of the men's 50 freestyle at CenturyLink Center. He returned to the sport in January 2011, after an eight-year hiatus in which he taught swimming, played in a band, finished college and moved past the burnout that halted his career.

Ervin won his semifinal heat in 21.74 seconds. That topped his personal best of 21.80 -- set 12 years ago -- and is the third-fastest time in the world this year. While he will swim Sunday for a spot on the team for the London Olympics, Natalie Coughlin secured her place Saturday with a sixth-place finish in the women's 100 free.

Coughlin, 29, swam a time of 54.44 to make her third Olympic team. She felt relieved to have an opportunity to win a 12th Olympic medal, which would tie her with Jenny Thompson and Dara Torres as the most decorated female swimmers in U.S. Olympic history. Ervin felt delighted to be the swiftest man in the semifinals, and more than a little wonderstruck to be there at all.

"I didn't think I'd be in this position again,'' Ervin said. "In a lot of ways, I'm very much surprised. But the vicissitudes of life, I guess we're always thrown for a loop at some time or another. I'm just going to go with it.''

Ervin felt burned out from an early age, he said, but stuck with the sport because he was so talented. At age 19, he won the gold in the 50 free and silver in the 400 free relay at the 2000 Olympics. A year later, he added world championships in the 50 and 100 free. Then, in 2003, he quit.

Ervin said he needed to break free of the rigid discipline and sacrifice required of an elite swimmer and explore life outside the pool. While teaching children to swim in New York City, he rediscovered the joy in the sport, and he resumed training at the University of California 18 months ago.

Coughlin was surprised at how she performed at the trials, too: She finished third in her signature event, the 100 backstroke, and seventh in the 100 butterfly. The 100 free represented her last hope of going to London.

The top two swimmers will compete in that event at the Olympics, and the third- through sixth-place finishers will be part of the 400 free relay team. Coughlin beat out Dana Vollmer by .17 of a second for sixth.

"This isn't the meet I visualized or anticipated going into this year,'' said Coughlin, who has medaled in all 11 Olympic events she has swum. "But right now, I couldn't be happier.''

Coughlin said she might have overtrained for the trials. She said she never has been motivated by surpassing Thompson and Torres, but she found herself distracted by the chatter about it. Coughlin added she was at peace with the way things played out, and she accepts that her primary role in London will be to support her teammates.

Also Saturday, Michael Phelps defeated Ryan Lochte to win the 200 individual medley and take a 2-1 advantage in their head-to-head matchup at the trials. Lochte won the 200 backstroke in his three-race night, and he and Phelps both advanced to Sunday's 100 butterfly finals.

Gophers senior Haley Spencer finished seventh in the women's 200 breaststroke in a time of 2:27.82.