Men's 400m Hurdles Semi-Final 1
dimanche 1 août 2021, 12h05 GMT – 17h05 GMT
| Nom | Temps | |
|---|---|---|
| 1 |  Karsten Warholm | 47.3″ |
| 2 |  Rai Benjamin | + 0.07″ |
| 3 |  Yasmaní Copello | + 0.58″ |
| 4 | Thomas Barr | + 0.96″ |
| 5 |  Kemar Mowatt | + 1.65″ |
| 6 |  Sokwakhana Zazini | + 1.69″ |
| 7 |  Ludvy Vaillant | + 1.72″ |
| 8 |  Joshua Abuaku | + 2.63″ |