Four events will crown medalists today and plenty of Americans are in the hunt for hardware.

Ryan Murphy is in contention for another medal at this year's Olympics, this time in the 200m back. Caeleb Dressel also returns to the pool for the men's 100m butterfly one night after winning gold in the 100m freestyle.

American duo Annie Lazor and Lilly King are both fighting for the top step of the podium in the women's 200m breaststroke, but they'll have to get past Olympic record holder Tatjana Schoenmaker to get there.

Find a full preview of today's events below.

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

Men's 100m Butterfly, Semifinals


Caeleb Dressel equaled the Olympic record of 50.39 seconds in his prelim on Thursday - not a bad start for the guy who many expect to win gold in this event.

He'll swim in the second semifinal alongside fellow American Tom Shields. Hungary's Kristof Milak, Olympic record holder and Tokyo gold medalist in the 200m butterfly, is another favorite to finish on the podium in this event. He headlines the Semifinal 1 field.

Women's 200m Breaststroke, Final


South Africa's Tatjana Schoenmaker set an Olympic record with a 2:19:16 in prelims, then followed it up by qualifying first from the semifinal with a 2:19:33. She's the favorite.

Americans Annie Lazor and Lilly King join Schoenmaker in the final, and both have medal aspirations. Standing in the way could be ROC's Evgeniia Chikunova, who beat out everyone not named Schoenmaker by over a second in the semifinal.

Men's 200m Backstroke, Final


American Ryan Murphy won gold in this event in Rio five years ago, and he's in the hunt to do it again. He's joined by teammate Bryce Mefford.

Evgeny Rylov (ROC) won gold in the 100m backstroke on Tuesday and posted the best time from the semifinal heats. Murphy was off his semifinal pace by almost a full second.

Women's 100m Freestyle, Final


Australian Emma McKeon set an Olympic record in prelims with a 52.13. She also led the field in the semifinal heats and was part of the Australia team that won gold in the 4x100m freestyle relay on Sunday.

After McKeon, it's a star-studded group that includes Cate Campbell (AUS), Penny Oleksiak (CAN), Abby Weitzeil (USA), Siobhan Bernadette Haughey (HKG) and current world record holder Sarah Sjoestroem (SWE). This field is packed.

Men's 200m IM, Final


Wang Shun (CHN) and Hagino Kosuke (JPN) shared the podium with some American swimmer named Michael Phelps in this event back in 2016. They're back in the final this year.

Michael Andrew (USA) also takes part after qualifying fourth from the semifinal. Duncan Scott (GBR), who's already had a successful Olympics with a gold medal in the 4x200m relay and a silver medal in the 200m freestyle, will be in the hunt for gold as well.

Women's 200m Backstroke, Semifinals


Australian Kaylee McKeown entered as one of the big favorites to win gold. She backed that up with the quickest time in prelims.

She's joined by Canadian Kylie Masse in Semifinal 2. Americans Rhyan White and Phoebe Bacon headline Semifinal 1 after posting two of the hottest times from the first round of heats.