Eric Shanteau, left, shown here with Ryan Lochte, set an American record in the 200-meter breaststroke this morning. (Darron Cummings, Associated Press)

INDIANAPOLIS, July 11 — The way he’s been swimming in recent months, Eric Shanteau figured he would eventually take down the American record in the 200-meter breaststroke.

But at just past 10 a.m. Saturday in a preliminary heat?

“That,” Shanteau said, “was definitely a surprise.”

Urged on by announcer Sam Kendricks, who riled a sleepy crowd at the Indiana University natatorium into a bit of a frenzy, Shanteau blazed through the first 100 in 1 minute, 01.90 seconds, and, sensing something special was going on, swam hard to the wall.

He finished in 2:08.43 seconds, going under Brendan Hansen’s 2006 mark of 2:08.50. That mark had stood as the world record until June, when Japan’s Kosuke Kitajima swam a 2:07.51 in Tokyo.

“Obviously, I was shooting for it, but not necessarily this morning,” Shanteau said. “It’s kind of funny that the first American record I would break comes in a preliminary swim.”

Shanteau, 25, who trains in Austin, Tex., can hardly believe how well this summer has gone.  Shanteau had surgery to remove a cancerous testicle shortly after the Summer Games in Beijing; he got back in the water to escape the stress of his fight with cancer. As many fellow Olympians vacationed and rested, Shanteau worked.

“I think I’ve made the best out of my situation,” Shanteau said. “My situation has been pretty s—— for the past two years. There’s definitely light at the end of the tunnel.”

Now, cancer-free and bulked up from hours in the weight room, Shanteau has qualified for the world championships in Rome in two events, the 100 breast and 200 individual medley, and he looks ready to add a third in the 200 breast final Saturday night.

He will also have the option of swimming in the 50 breast in Rome, though Shanteau said swimming four individual events might be too taxing.

“It’s a lot,” Shanteau said. “People see Michael [Phelps] doing 50 million events. We’re not all like Michael.”

For the moment, it’s great to be Eric Shanteau.

Shanteau’s parents are here watching, another bonus for the Georgia native. His father, Rick, found out he had terminal lung cancer about a year before Shanteau received his diagnosis. But unlike his son, Rick Shanteau did not have the option of surgery, or the hope of being cured.

“He’s here, two years after being diagnosed,” Shanteau said. “I think for the situation he’s in, and what he was given, you can’t ask for anything more.

“It’s everything,” Shanteau also said. “All aspects of my life are going very well right now.”

Phelps Trains, Improves

Michael Phelps worked out lightly Saturday morning, swimming about 4,000 yards. Phelps, who dropped out of the men’s 100 free with neck soreness, appeared to be in good shape.

“He said it’s not 100 percent, but it’s probably 90 percent,” his coach Bob Bowman said.

Top Qualifiers

Women’s 100 free: Dana Vollmer, 54.21; Amanda Weir, 54.25; Christine Magnuson, 54.45; Lacey Nymeyer, 54.52; Caitlin Geary, 54.60; Julia Smit, 54.91; Kara Lynn Joyce, 54.98; Kate Dwelley, 55.06

Women’s 200 breast: Keri Hehn, 2:26.05; Rebecca Soni, 2:26.73; Elizabeth Tinnon, 2:27.09; Ashley Wanland, 2:27.55; Sara Nicponski, 2:27.56; Megan Jendrick, 2:27.80; Elizabeth Smith, 2:28.50; Justine Mueller, 2:28.54

Men’s 200 breast: Eric Shanteau, 2:08.43; George Klein, 2:11.25; Scott Spann, 2:12.33; Robert Lovelace, 2:12.43; Jack Brown, 2:13.68; Bart Steninger, 2:14.22; Aaron Opell, 2:16.03; Nolan Koon, 2:16.03

Men’s 200 back: Tyler Clary, 1:55.37; Aaron Peirsol, 1:55.78; Ryan Lochte, 1:55.99; Matt Grevers, 1:57.04; Rexford Tullius, 1:57.28; David Russell, 1:58.00; Nick Thomas, 1:58.09; Timothy Johnson, 1:59.47

LOCAL NOTES: North Baltimore Aquatic Club’s Nick Thoman, 23, posted the seventh-fastest qualifying time in the 200 back heats; Austin Surhoff, 18, of NBAC qualified for Saturday night’s B final in 2:02.14; Virginia’s Daniel Johnson, 21, (2:04.14) and Rockville-Montgomery’s Andrew Relihan, 19, (2:04.28) made the C final. Rockville-Montgomery’s Eric Friedland, 19, made the C final in the 200 breast in 2:19.31; he will be joined by John Azar, 21, of the University of Virginia, who finished in 2:20.00. Katherine Radloff of the Arlington Aquatic Club posted the 18th best time in the 100 free heats (56.06) earning a spot in the C final.