OMAHA - Michael Phelps showed up for the U.S. Olympic swimming trials Saturday with a bushy, Carl Pavano-style mustache and a secret. When he took a razor to his facial hair, he revealed more than just his upper lip.

Phelps had been coy about whether he would swim the 400-meter individual medley, the first race of the eight-day trials that opened Monday and the first potential meeting with rival Ryan Lochte. On Sunday, he tweeted a photo of his clean-shaven face, signaling to the world that the game was on.

Though Lochte got the better of him in Round 1 on Monday night, Phelps was pleased to make his fourth Olympic team -- and some measurable progress -- in an event he thought he had left behind.

Lochte, the current world champion in the 400 IM, won the race in 4 minutes, 7.06 seconds to earn the first spot on the U.S. swimming team for next month's London Olympics. Phelps, the world-record holder in the event, joined him by finishing second in 4:07.89 at CenturyLink Center.

Olympians also were named in the men's 400-meter freestyle, with Peter Vanderkaay and Conor Dwyer going 1-2, and in the women's 400 IM, where winner Elizabeth Beisel and runner-up Caitlin Leverenz claimed their places on the team. On a night that included poolside pyrotechnics and 11,207 raucous fans, Lochte and Phelps set the match to a rivalry expected to burn all the way to London.

"I'm very pleased,'' said Phelps, 26, who has said these will be his last Olympics. "There was a lot of discussion about me doing [the 400 IM]. It came down to, I wanted to do it. This is an event I've been doing a long time. I'm happy to get this first monkey off my back.''

After setting the world record in the 400 IM at the Beijing Olympics, Phelps vowed he would retire from that grueling event. But he always has placed a premium on achieving things that never have been done, and the 400 IM presented a unique opportunity. As the 2004 and 2008 gold medalist in that event, Phelps could have the chance to become the first swimmer to win the same Olympic race three times in a row.

Phelps had spent the past six weeks in Colorado Springs, training at altitude and trying to recapture the form that brought him a record eight gold medals at the Beijing Olympics. While he slacked off his training and lost focus after those Games, Lochte, 27, rose out of his shadow to surpass him. At the 2011 world championships, Lochte won gold medals in all five events he swam, and he joined Phelps as a pop-culture presence on magazine covers and in advertisements.

Phelps said Lochte had "destroyed'' him over the past couple of years -- including at the 2011 worlds, when Lochte took gold to Phelps' silver in the 200-meter freestyle and the 200 IM.

"I tried to get away with faking as much as I could,'' Phelps said. "I saw the results were pretty crappy. I think I've been able to do things that are hopefully going to show good results this week.''

That began with the 400 IM. After setting it aside for a year and a half, Phelps put it back into his program earlier this year. On Monday, he fought through what he called a "painful'' race, buoyed by the flames that shot up from the side of the pool and a crowd energized by a tight three-way race among Phelps, Lochte and Tyler Clary.

Lochte took command during the breaststroke leg and pulled away, looking smooth and powerful.

"The first race is always the hardest,'' he said. "Now I can relax, and whatever happens, happens.''

The two will go head-to-head again Tuesday in the 200-meter freestyle. They could compete against each other as many as six times, depending on which events each chooses to swim.

Coach Bob Bowman said there is plenty of room for Phelps to fine-tune the 400 IM before the Olympics. He didn't expect to beat Lochte this time, but he liked the time and the result -- and the tone Phelps has set.

"He needed to have a race at this level to know where he is,'' Bowman said. "I feel pretty good about it. This is the catalyst for everything else.''