Three of Team USA’s brightest swimming stars chase gold medals on the fourth day of competition from the Tokyo Aquatics Center.

The medal races come thick and fast on Tuesday, with all four finals taking place consecutively, book-ended by a trio of semifinals.

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

Women’s 200m Freestyle – Semifinals


The headliners of Day 3 return to lead off Tuesday’s action as Katie Ledecky and Ariarne Titmus race the women’s 200m freestyle semifinals.

It comes just one day after Titmus beat Ledecky in the 400 free, the first time Ledecky failed to win an in individual Olympic competition.

Men’s 200m Freestyle – Final


Kieran Smith is the United States’ lone participant in the 200 free final but is in the mix for his second medal of the Tokyo Games. Smith, the 400 free bronze medalist earlier in the week, enters with the second-fastest semifinal time behind Great Britain’s Duncan Scott.

Women’s 100m Backstroke ¬– Final


The Olympic record has been lowered four times by three different swimmers so far in Tokyo as the world record mark – set by Australian Kaylee McKeown at 57.45 – looms in peril.

Regan Smith earned the top seed in the final with a time of 57.86. Prior to McKeown’s best-ever swim in June, Smith held the world record.

Kylie Masse of Canada is a medal contender as well.

Men’s 100m Backstroke – Final


Ryan Murphy is 52 seconds away from successfully defending his 100 back gold medal from the Rio Olympics.

He takes on rivals Mitch Larkin of Australia and Russian athlete Evgeniy Rylov.

Women's 100m Breaststroke – Final


Lilly King renews her contentious battle with Yulia Efimova, a duel that erupted in Rio when King wagged her finger at her Russian rival, who had previously been suspended for a drug violation.

Alaska's Lydia Jacoby also is in the field.

Men’s 200m Butterfly – Semifinal


American Zach Harting faces a star-studded pool of rivals in the first semifinal that features world record holder Kristof Milak of Hungary, Chinese Taipai’s Wang Kuan-Hung and Chad Le Clos of South Africa, gold medal winner in London and silver medallist in Rio.

American Joseph Bentz looks to advance out of the second semifinal.

Women’s 200m Individual Medley – Semifinal


Kate Douglass and Alex Walsh hope to advance out of their respective semifinals. Walsh swims with defending Olympic champion Katinka Hosszu the first semifinal.