Phelps, the two-time defending Olympic champion in the 100 fly, advanced to the final with another fastest time of 2012, powering away to win his heat in 51.35. Lochte tied for the sixth-fastest time in the semifinals (52.47), but this isn't one of his specialties. He'd need to pull a big upset to earn another Olympic event.

But, said his coach, Gregg Troy, ''Ryan thrives on challenges.''

Lochte seemed to have Phelps' number when he beat him twice at last year's world championships, then kept the dominance going with a convincing win on the first night of the trials in the 400 individual medley.

But Phelps edged Lochte in the 200 freestyle, and now he's got two wins in a row against the only swimmer who seems capable of preventing him from making another serious run at eight gold medals in London.

The two slapped hands while hanging on the lane ropes, then headed for the edge of the pool, fully aware the races that really matter are still to come.

''It feels good to be back on that side, but I'm sure that's not going to be the end of us going back and forth,'' Phelps said. ''I'm sure there's going to be some more races like that over the next few weeks.''

After he received his medals, the sellout crowd of more than 13,000 serenaded Phelps with a rendition of ''Happy Birthday.'' Then he trotted around the deck to hug his mom and sister.

In other events on the sixth night of the trials, Jessica Hardy made up for the disappointment of missing out on the Beijing Games because of a failed drug test, winning the 100 freestyle. Seventeen-year-old Missy Franklin moved a step closer to having a seven-event program in London, finishing second behind Hardy in 54.15, while 11-time Olympic medalist Natalie Coughlin missed out on her last realistic chance at an individual Olympic race.

''That was all my heart in that race right there,'' said Hardy, who won with a time of 53.96.

Coughlin finished sixth, the last spot that can earn a possible berth on the 400 freestyle relay. But, at best, she would probably only get a morning swim at these games, a far cry from the six medals she won in China.