Caeleb Dressel, the top star in men's swimming, had a relatively muted roll in the proceedings in the pool in Tokyo prior to Day 6. That changed Thursday.
Dressel won the most classic of Olympic races, the 100m freestyle.
Elsewhere, Katie Ledecky and Ariarne Titmus matched up for the third time at the Tokyo Games, but this time with heir entire teams behind them in the 4x200m freestyle relay.
Relive the action below with full highlights.
Watch all the action from the Tokyo Games Live on NBC
Men's 800m Freestyle, Final
Bobby Finke came out of absolutely nowhere.
The lone American in the men's 800m freestyle won the event's Olympic debut in 7:41.87.
At the 750 meter mark, he was not in the picture for a medal, let alone gold. But a monumental final length of the pool saw him surge past Gregorio Paltrinieri (ITA), Mykhailo Romanchuk (UKR) and Florian Wellbrock (GER) to be first to the wall.
"I just really wanted to get my hand on the wall," Finke said. "I was able to switch into another gear."
Men's 200m Breaststroke, Final
Aussie Zac Stubblety-Cook mounted a massive late charge to win his first Olympic gold medal in 2:06.38.
Stubblety-Cook trailed Dutch swimmer Arno Kamminga by over a second at the 150 mark but closed in 32.21 to touch first.
Kamminga took silver, ahead of Matti Mattsson of Finland for bronze.
American Nic Fink finished fifth.
Women's 100m Freestyle, Semifinals
Emma McKeon of Australia leads a field filled with former Olympic champions. McKeon set an Olympic record in the preliminary heats, and while she did not lower that record in the second semifinal, she qualified first in 52.32.
Within a second of her time though, you'll find Australia's Cate Campbell, Sweden's Sarah Sjostrom and Canada's Penny Oleksiak.
That's 15 combined Olympic medals headed to a star-studded final.
That final will also include American Abbey Weitzeil, who qualified seventh in 52.99.
Men's 100m freestyle, Final
Caeleb Dressel got it done in the men's 100 freestyle.
Dressel out-touched defending gold medalist Kyle Chalmers (AUS) by .06 to win gold in Olympic record time.
Russian athlete Kliment Kolesnikov took bronze.
Men's 200m backstroke, Semifinal
Both Americans Bryce Mefford and defending gold medalist Ryan Murphy are safely into the final.
Neither won their second semifinal, though, which went to Great Britain's Luke Greenbank.
Russian athlete Evgeniy Rylov, the 100 back gold medalist in Tokyo, was the only swimmer to break 1:56, winning the first semi in 1:54.45.
Women's 200m butterfly, Final
China's Zhang Yufei dominated from the start, winning in an Olympic record of 2:03.86. Zhang got out to a huge lead at 100 meters and did not give up any ground coming home.
Americans Regan Smith and Hali Flickinger took the other two spots on the podium.
2019 world champion Boglarka Kapas of Hungary finished fourth.
Women's 200m breaststroke, Semifinal
South Africa's Tatjana Schoenmaker came within .05 of the world record in the heats with a blistering time of 2:19.16. She did not lower that mark in the semifinal, but did advance as the top seeded swimmer.
Both Americans, Annie Lazor and Lilly King, qualified for the final, going 2:21.94 and 2:22.27, respectively.
Men's 200m IM, Semifinal
Chase Kalisz, the 400 IM gold medalist, struggled in his first semifinal, finishing sixth and missing the final.
The stronger American in the event, Michael Andrew, advanced to the final but fished behind Wang Shun of China, who advanced as the top seed.
Japan's Seto Daiya and defending gold medalists Hagino Kosuke will the swim the final as well.
Women's 4x200m freestyle, Final
The United States, behind a gutsy 1:53.76 anchor leg by Katie Ledecky, beat out heavy favorites Australia in the final of the women's 4x200m freestyle relay at the Tokyo Olympics.
The only thing more shocking than that outcome is the fact that it did not result in a gold medal.
China emerged as the winners of a thrilling relay in world record time at 7:40.33.
The United States took silver, with bronze going to Australia.