On Thursday, Ledecky won the 400m freestyle in 3 minutes, 56.81 seconds at a Tyr Pro Series meet in Fort Lauderdale, Florida.

The World Athletics Relays, an event crowning champions in 4x100m and 4x400m events, airs live this Saturday and Sunday on Peacock and CNBC. Coverage begins each day at 7 a.m. ET from Guangzhou, China ...