Indianapolis, IN (My Sportsbook) - Nathan Adrian won the men's 100-meter freestyle final Friday night at the USA Swimming championships, his victory made easier after record-setting Olympian Michael Phelps pulled out of the competition earlier in the day.

Phelps, who won three National titles, set a world record this week and holds the American mark in the 100 free, dropped out due to neck pain. He has still qualified to compete in the 100m and 200m butterfly, as well as the 200m freestyle in Rome at this month's world championships. He'll also likely compete in all of the men's relays.

"Yesterday, I woke up with a crick in my neck. I got it worked on after prelims, before finals and after finals," Phelps said. "Then I woke up this morning and it was worse. When I came here and hopped in the water, I could barely turn to breathe. I'm disappointed I'm not swimming here, but the 200 fly is definitely my better race so I need to prepare for that."

Adrian, part of the USA's gold medal-winning 400-meter freestyle relay team in Beijing, posted a time of 48 seconds to win the race, beating David Walters (48.17) and Garrett Weber-Gale (48.19).

Also Friday, Ryan Lochte won the men's 200m individual medley in 1 minute, 54.56 seconds; Elizabeth Beisel captured the women's 200m backstroke in 2:08.80; and Kathleen Hersey came out on top in the women's 200m butterfly in a winning time of 2:06.44.