Rex Maurer Throws Down 3:43.33 400 Freestyle for U.S. Open Record, 3rd All-Time US Performer

2025 U.S. NATIONAL CHAMPIONSHIPS

After shattering the American Record in the 500 freestyle during the NCAA season, Rex Maurer was expected to make a splash in the long course pool. He met, and even exceeded those expectations tonight with a U.S. Open Record in the 400 freestyle to win the event at Nationals.

Maurer posted a time of 3:43.33, smashing his personal best of 3:46.52 with his performance. In the process, he also took down Larsen Jensens longstanding U.S. Open Record of 3:43.53, set back at the 2008 Olympic Trials. His time also makes him the 3rd-fastest American in history, only behind Peter Vanderkaay (3:43.11) and Jensen (3:42.78), with both swimmers setting their best times at the 2008 Olympic Games.

Top 5 All-Time US Performers – Men’s 400 Freestyle

  1. Larsen Jensen – 3:42.78 (2008 Olympic Games)
  2. Peter Vanderkaay – 3:43.11 (2008 Olympic Games)
  3. Rex Maurer – 3:43.33 (2025 US National Championships)
  4. Conor Dwyer – 3:43.42 (2016 Olympic Games)
  5. Connor Jaeger – 3:43.79 (2016 Olympic Games)

In terms of worldwide ranking, Maurer now ranks 2nd in the world this season behind German Lukas Märtens, who set a new World Record earlier this season with a 3:39.96. With Märtens as the heavy favorite in Singapore, Maurer will certainly be in the conversation for a medal if he can repeat that performance.

2024-2025 LCM Men 400 Free

LukasGER
MÄRTENS
04/12
WR 3:39.96
2Rex
MAUER
USA3:43.3306/06
3Oliver
KLEMET
GER3:43.4004/12
4Samuel
SHORT
AUS3:43.8404/04
5Florian
WELLBROCK
GER3:45.2904/12
View Top 26»

In addition to the 400 freestyle, Maurer is slated to swim the 4×200 freestyle relay in Singapore after finishing 3rd in the 200 freestyle (1:45.13). His final event of the Championships will be the 800 freestyle on Saturday, where he is seeded 3rd overall (7:51.19).

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John26
18 hours ago

Didn’t Klemet go 3:42 this year? So Mauer is #3

Steve Nolan
21 hours ago

When Mauer goes out fast

comment image

Smglsn12
1 day ago

It’s very interesting that Maurer is still solidly behind Marchand in the 500 but seemingly well ahead of him in the 400 – is there a 3:41 for Marchand or is his 500 just all underwaters and his actual freestyle swimming isn’t quite there?

swammer
Reply to  Smglsn12
22 hours ago

The latter

Joel
1 day ago

Maurer will have to be 3.41 if he wants a medal in Singapore …. at least.

Swimgeek
Reply to  Joel
1 day ago

Thanks, you’re good at math.
For the rest of us, we’re kinda excited about the emergence of the best young middle-D tandem in USA history.

Joel
Reply to  Swimgeek
1 day ago

Well the article says he’ll be in the conversation for a medal if he repeats today’s performance.

IRO
1 day ago

That American record’s days are numbered.

holy moly
1 day ago

holy moly

Ole 99
1 day ago

Misspelled his name in the list.

PFA
1 day ago

Congrats Rex my friend well deserved! Luka just became the youngest swimmer to qualify for a Worlds team since MP (younger than Heilman) wild times indeed

About Nicole Miller

Nicole Miller

Nicole has been with SwimSwam since April 2020, as both a reporter and social media contributor. Prior to joining the SwimSwam platform, Nicole also managed a successful Instagram platform, amassing over 20,000 followers. Currently, Nicole is pursuing her B.S. in Biomedical Engineering at Worcester Polytechnic Institute. After competing for the swim …

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