Georgia swimmer Chase Kalisz did not want to leave Tokyo without knowing he had done his best.

But he didn’t realize he would kickstart a historic day for U.S. swimming.

Kalisz, the silver medalist at the Rio Games in 2016, won the 400 meters individual medley on Sunday morning (Saturday night, Pacific) to lead a medal haul for the Americans. They won six medals in one day for the first time in Olympic history.

One of them went to 4X100 meter relay teammates Simone Manuel of Stanford and Abbey Weiziel of Cal.

The day was better than Kalisz, 27, could have imagined. He still felt as if he had let his country down at the Rio Games in 2016 when finishing second in the United States’ signature swim event, the grueling 400 meters individual medley.

Kalisz called it a special kind of pain after he and training partner Jay Litherland finished first and second to get the United States off to a rollicking start at the Summer Olympics.

“That one definitely hurt more than any other,” Kalisz said of his victorious race. “I actually vowed I would make it hurt more than any other and give it my best to accomplish this.”

The United States won two more medals in the women’s 400 IM and bronze medals in the men’s 400 freestyle and women’s 4X100 relay for a stunning start to the Tokyo Games. Americans won six of the 12 medals available on the first day of swim finals.

It started when Kalisz built a .25-second lead in the third leg, the breaststroke, to take a commanding margin into the freestyle. Litherland, on the other hand, rallied in the final, lunging moments to grab a silver medal.

“Once that last 75 hits everything shuts down and you go blank and let whatever take the way,” said Litherland, who was born in Osaka, Japan. “Without a crowd, it still felt like a lot of people were in the stands cheering us on.”

Nothing was bigger than pool mates taking the gold and silver in the four-stroke event once owned by Michael Phelps.

With Phelps serving as a color commentator for NBC Sports, Kalisz swam a controlled race to win in 4 minutes 9.42 seconds. Litherland, who started the final leg in sixth place, touched the wall in 4:10.28, just ahead of bronze medalist Brendon Smith of Australia.

Kalisz, who won the silver medal in Rio, is the sixth American to win the event in the past seven Olympics.

“This was my redemption story,” he said.

As expected, Australia dominated the women’s 400 relay, breaking its three-year-old world record with a time of 3:29.69.

TOKYO, JAPAN – JULY 25: Simone Manuel of Team United States competes in the Women’s 4 x 100m Freestyle Relay Final on day two of the Tokyo 2020 Olympic Games at Tokyo Aquatics Centre on July 25, 2021 in Tokyo, Japan. (Photo by Tom Pennington/Getty Images) 

The drama was who would join the Aussies on the podium. In a race bringing memories of the Rio Games 100 freestyle, Stanford’s Manuel and Canada’s Penny Oleksiak went stroke for stroke to the wall in the anchor leg.

In 2016, the rivals tied as Manuel became the first Black woman to win a gold medal in swimming. This time Oleksiak was slightly faster in chasing down Manuel for the silver medal.

The Americans, behind Weitzeil’s second leg, finished third. Manuel was timed in 52.96, well off her American record of 52.09. But the former Stanford star didn’t qualify for the 100 meters this year after faltering at the U.S. Olympic trials in June.

In a touching moment afterward, Manuel revealed that she had been diagnosed with overtraining syndrome in late March. She left Stanford to take a break at home near Houston before preparing for the pressure-packed trials.

After discussing the situation publicly Manuel looked looser and rallied to win the 50 freestyle sprint to qualify for her second Olympics.

While back training, Manuel, 24, said she tried a few 100 freestyle sets to break up the monotony of her sprint routine. She and U.S. Olympic coach Greg Meehan, who doubles as the Stanford coach, saw big improvements.

Meehan gave Manuel the keys to the car Saturday. She learned the night before she would be on the relay giving Manuel a chance for two medals in Tokyo.

The men were not the only ones who dominated the 400 medley.

Emma Weyant, 19, of Sarasota, Florida, won the silver in the women’s 400 IM, 0.68 seconds behind gold medalist Yui Ohashi of Japan. Hali Flickinger, 27, was third as the teammates became the first American women to earn multiple medals in the event since the 1968 Olympics in Mexico City.

Kieran Smith, a University of Florida graduate, sprinted to the finish to earn a bronze medal in the 400 freestyle.

Weitzeil, who is scheduled to swim the 50 and 100 freestyles, said the other teammates motivated the relay swimmers.

“Just seeing our team get on the podium, get on the podium, get on the podium again, it fired us up,” she said.

Kalisz said he wanted to ignite the United States with a big splash. But an hour after his victory, the Maryland swimmer still hadn’t processed it.

“I bent down and the starter beeped and I went,” he said. “Everything else has been a blur right now.”