The three-fastest men's 400m hurdlers easily advanced to the semis. All three are in top form--each has broken 47 seconds this season--after struggling with injuries during the post-Olympic years.
The reigning Olympic champ and world record holder, Karsten Warholm, is looking like his former self. If you've never seen him run, he's nuts. He goes all out at the gun and finds a way to hold on. He's got the slowest flat 400 speed but he runs with so much strength that it doesn't matter. Case in point: his best 400mH time is only a second slower than his open 400m time.
Brazil's Alison dos Santos runs a more measured race. The slender, 6-foot-7 strider was the best in the world in 2022 but missed much of last season due to injury.
American Rai Benjamin was bridesmaid to Warholm at the 2019 and 2023 world championships and the 2020(21) Olympics, and he finished behind dos Santos at the 2022 World Championships. I think he's done being second fiddle. He bounced back from a mid-season injury last year to win Diamond League with 2023's fastest time and he's beaten Warholm and dos Santos multiple times this season, again posting a world-leading time. He has the fastest flat 400 time (44.2) and will feature in the men's 4x4 relay, as well.
Also representing the Red, White and Blue are CJ Allen and Trevor Bassitt. Dr. Allen easily advanced out of his heat but Bassitt ran a terrible prelim and will have to rely on a good showing in the repechage to reach the semis.
TLDR summary: this event promises to be one of the best finals of the Games. We could very likely see another world record. And if you can't crack 47 seconds, you likely have no chance of reaching the podium.