INDIANAPOLIS -- Michael Phelps defeated an Olympic medalist for the second consecutive night, and was still looking to improve.

Phelps, the 17-year-old standout from Baltimore, won the 200-meter freestyle in the U.S. National Spring Swimming Championships on Thursday.

Phelps finished in 1 minute, 47.37 seconds, beating Klete Keller. Keller, the bronze medalist in the 400 meters at the 2000 Olympics, was second in 1:47.74.

''I think I misjudged the race,'' Phelps said. ''I was hoping to pull away in the third and fourth 50, but I swam their race instead of my own. It was definitely a learning experience.''

Still, Phelps came within .64 of the national record of 1:47.08 established by Josh Davis in 2000. Davis finished seventh Thursday in 1:52.03.

In the 200-meter backstroke Wednesday, Phelps defeated Lenny Krayzelburg, who won three gold medals at the Sydney Olympics.

Tom Wilkens secured his 16th national title by winning the 400-meter individual medley in 4:16.75, then compared Phelps' impact on the sport to Michael Jordan's on the NBA.

''Michael is raising the bar, making all of the sport better,'' Wilkens said of Phelps, who has won nine national titles. ''He's making me better, too.''

Wilkens, 27, moved into a tie with Chad Carvin for most national titles. Carvin finished fifth in the 200 freestyle at 1:49.75.

Lindsay Benko, another Olympian, took first in the women's 200 freestyle. She led from start to finish, clocking in at 2:00.58 to 2:01.10 for Rhiannon Jeffrey. That was a reversal of the finishing order in the 100 freestyle Wednesday.

Kaitlin Sandeno, an Olympian from the University of Southern California, won the women's 400 individual medley in 4:45.48.

Southern Methodist swimmers Lisa Wanberg, Laura Pomeroy, Georgina Lee and Lotta Wanberg won the women's 400 freestyle relay in 3:48.86.

Nathaniel Dusing, Neil Walker, Joshua Davis and Garrett Weber-Gale, swimming for the Circle C Swim Team, won the men's 400 freestyle relay in 3:20.03.