The two brightest stars in the sport of swimming, Caeleb Dressel and Katie Ledecky, close in on gold medals in their most well-known events on the penultimate day of swimming at the Tokyo Olympics.

Saturday's finals session begins with Dressel competing in the 100m butterfly, the event in which he owns the world record. The 100 fly final will mark the first of as many as three races Dressel could swim in the session, along with the 50m freestyle semifinals and the mixed 4x100m medley relay final.

While Dressel catches his breath, Ledecky will swim for her third-straight Olympic gold medal in the women's 800m freestyle after first winning it as a 15-year-old in London. Once again, she meets Australia's Ariarne Titmus in the final. Titmus has won gold in both prior individual events to include both swimmers in Tokyo, the 200 free and 400 free.

Finally, the mixed 4x100m medley relay — the only event to include both male and female swimmers — makes its Olympic finals debut to close out the session.

Watch the action LIVE in primetime on NBC beginning at 9:30 p.m. ET or stream the entire session LIVE on NBCOlympics.com and the NBC Sports app.

Men's 100m Butterfly, Final

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Dressel, the world record holder at 49.50, became the first person ever to go sub-50 seconds at the Olympics in the semifinals at 49.71.

He's the heavy favorite in his most dominant event.

Hungary's Kristof Milak, the gold medalist in the 200 fly, is the favorite to win the race for silver.

Women's 200m Backstroke, Final

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The United States, Australia, Canada and China all qualified both of their swimmers to the final of the women's 200 back, which stacks up as a four-nation battle.

The Americans, Rhyan White and Phoebe Bacon, are both among the top medal contenders but its the Aussies, Kaylee McKeown and Emily Seebohm, who are favored.

Women's 800m Freestyle, Final

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Prepare for Ledecky vs. Titmus Part Three.

After Titmus took the middle distance races, both swimmers enter Ledecky territory in the 800 free, the event Ledecky has dominated since her teenaged years. Ledecky owns the top 23 times in history in the event.

She burst onto the scene in the 800 at the London 2012 Olympics, winning the gold medal as a 15-year-old. In Tokyo, she'll swim beside teammate Katie Grimes, who coincidently is 15 herself.

Men's 50m Freestyle, Semifinals

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Dressel races the second semifinal and is expected to advance, though his power may be slightly neutralized after the 100 fly.

American Michael Andrew also joins Dressel in semifinal No. 2.

France's Florent Manadou, the 2012 Olympic champion, headlines the contingent in the first heat.

Women's 50m Freestyle, Semifinals

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Can Simone Manuel make the final of her only individual event in Tokyo?

It won't be easy with a stacked field of female sprinters competing with her for the eight lanes.

2019 world champion and world record holder Sarah Sjostrom, 2016 Olympic champion Pernille Blume, 2012 Olympic champion Ranomi Kromowidjojo and perennial sprint contender Cate Campbell all eye a marquee final.

Abbey Weitzeil is the other American competing in the event.

Mixed 4x100m Medley Relay, Final

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The newest Olympic relay, and the first to include men and women swimming with and against each other, contests its first Olympic final.

The United States, likely featuring Dressel, is the presumptive favorite but Great Britain, China and Australia could threaten for gold in an unpredictable final.