Dressel won two more golds Sunday at the Tokyo Aquatics Centre, first winning the men's 50-meter freestyle in an Olympic-record time of 21.07 seconds, then returning about an hour later to swim the butterfly leg and help the U.S. set a world record in winning the 4x100 medley relay, a race the Americans have never lost.
With his fifth victory, Dressel joined Americans Michael Phelps, Mark Spitz and Matt Biondi, as well as East Germany's Kristin Otto, as the only swimmers to win as many as five golds at one Olympics. Phelps did it three times.
"I'm proud of myself. I feel like I reached what my potential was here at these games,'' Dressel said. "It was just really fun racing."
He doesn't plan to savor his triumph for long, right on par for a guy who said a few days ago that "swimming was a lot more fun when no one knew who I was.''
They certainly know who he is now.
"I give myself a pat on the back and then I just want to go home, put it away and move forward," Dressel said.
In the 50 free, Dressel cruised to a relatively easy victory in the frenetic dash from one end of the pool to the other. France's Florent Manaudou repeated as the Olympic silver medalist in 21.55 and Brazil's Bruno Fratus claimed the bronze in 21.57, edging out American Michael Andrew for the final spot on the podium.
In the men's medley, the Americans were trailing two other teams when Dressel dived in for the fly. Just like that, he blew by Britain and Italy with a blistering leg of 49.03 seconds, more than a second faster that anyone else.
Zach Apple made the lead stand up on the freestyle to give the Americans a world record of 3 minutes, 26.78 seconds, eclipsing the mark of 3:27.28 they set at the 2009 Rome world championships in rubberized suits.
Ryan Murphy and Andrew joined Dressel and Apple on the winning team, ensuring the Americans remained unbeaten in the medley relay, the final swimming event at the Tokyo Aquatics Centre.
Britain won silver, and Italy won bronze.
Dressel entered the day with golds in the 4x100-meter freestyle relay, 100-meter freestyle and 100-meter butterfly, in which he set the world record.
American Bobby Finke used a strong finishing kick to win the grueling men's 1,500-meter freestyle race for his second gold medal of the Olympics.
Just as he did in winning the 800-meter freestyle, Finke stayed closed throughout the 30-lap race and turned on the speed at the end. He touched in 14:39.65.
The top four were close nearly the entire race, often separated by less than a second at the turns. But that was right where Finke needed to be. After his closing lap in the 800, he knew he had the speed at the end to beat everyone else.
"I was confident in my ability to come home," Finke said.
Finke was perhaps the biggest American surprise at the pool. Relatively unknown before the U.S. trials, he became the first American male to win the 1,500 since Mike O'Brien at the 1984 Los Angeles Games.
"I came in not really expecting to get a medal or anything," Finke said, "and I come out of it with two golds."
Australia's Emma McKeon made history Sunday by winning her sixth and seventh medals in Tokyo, the most ever in a single Olympics by a female swimmer. The only men to do it are Phelps, Spitz and Biondi.
McKeon won the women's 50-meter freestyle in an Olympic-record time of 23.81 seconds. Sweden's Sarah Sjostrom won the silver, and Denmark's Pernille Blume, the defending Olympic champion, took bronze. American Abbey Weitzeil was last in the eight-woman field.
Less than an hour later, McKeon got her historic seventh medal when she took the butterfly leg and helped the Aussies win the 4x100 medley relay in an Olympic-record 3:51.60. Weitzeil couldn't quite hold off Cate Campbell, leaving the U.S. with a silver at 3:51.73. The bronze went to Canada (3:52.60).
McKeon is only the second woman in any sport to win seven medals at an Olympics, joining Soviet gymnast Maria Gorokhovskaya, who claimed two golds and five silvers at the 1952 Helsinki Games.
"It still feels very surreal,'' said McKeon, a 27-year-old from Brisbane, Australia. "It's going to take a little bit to sink in. I'm very proud of myself.''
The Associated Press contributed to this report.