arena Swim of the Week: 15-Year-Old Yi Zheng Drops 4:20.55 400 IM At U.S. Nationals

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Disclaimer: Swim of the Week is not meant to be a conclusive selection of the best overall swim of the week, but rather one Featured Swim to be explored in deeper detail. The Swim of the Week is an opportunity to take a closer look at the context of one of the many fast swims this week, perhaps a swim that slipped through the cracks as others grabbed the headlines, or a race we didn’t get to examine as closely in the flood of weekly meets.

Carmel Swim Club’s Yi Zheng had an incredible swim in the preliminaries of the men’s 400 IM on Thursday morning at the U.S. National Championships in Indianapolis.

Zheng, 15, knocked nearly two seconds off his personal best time to clock 4:20.55, placing him 12th overall in the prelims and thus earning him a berth in the consolation final. He set his previous best of 4:22.21 at the 2025 Central Zone Speedo Sectionals this past March.

Compared to his previous PB, Zheng was much quicker at Nationals on the front half, turning in 2:06.88 at the 200-meter mark compared to 2:09.90 at Sectionals. He held his splits relatively even over the next three 50s, but coming home, didn’t have the closing push he did in March, closing in 30.21 after he was previously 28.82.

Split Comparison

Despite still being just 15, Zheng now ranks 10th all-time in the boys’ 15-16 age group among Americans, having come into the meet ranked 24th with his former best time.

Sixteen-year-old Luka Mijatovic also set a new best time in the 400 IM at Nationals, clocking 4:16.18 in the prelims to move into 4th all-time in the 15-16 age group.

All-Time Performers, U.S. Boys’ 15-16 400 IM (LCM)

Note that the USA Swimming rankings include Marci Barta in 9th, who is a Hungarian native.

1. Carson Foster (Mason Manta Rays), 4:14.73 – 2018
2. Michael Phelps (North Baltimore Aquatic Club), 4:15.20 – 2001
3. Sean Grieshop (Nitro Swimming), 4:15.67 – 2015
4. Luka Mijatovic (Pleasanton Seahawks), 4:16.18 – 2025
5. Gunnar Bentz (Dynamo Swim Club), 4:17.43 – 2012
6. Maximus Williamson (North Texas Nadadores), 4:17.58 – 2022
7. Sean Green (Long Island Aquatic Club), 4:18.62 – 2023
8. Jake Foster (Mason Manta Rays), 4:19.40 – 2017
9. Cooper Lucas (Lakeside Aquatic Club), 4:19.95 – 2021
10. Yi Zheng (Carmel Swim Club), 4:20.55 – 2025

In the consolation final, Zheng added time, ultimately placing 16th in 4:26.23, while Mijatovic, racing in the ‘A’ final, finished 5th in 4:16.75.

Earlier in the meet, Zheng raced the 200 breaststroke, placing 26th in the prelims in a time of 2:15.48 before placing 2nd in the Junior ‘D’ final in 2:15.91. He owns a best time of 2:15.47, also set at Sectionals in March, which ranks him 24th all-time in the boys’ 15-16 age group.

Zheng is scheduled to race the 200 IM on Saturday, where his lifetime best of 2:03.23 (also from Sectionals) ranks 22nd all-time in the age group.

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