Men's 400m Hurdles Semi-Final 3
dimanche 1 août 2021, 12h25 GMT – 17h25 GMT
| Nom | Temps | |
|---|---|---|
| 1 |  Kyron McMaster | 48.26″ |
| 2 | Rasmus Mägi | + 0.1″ |
| 3 |  David Kendziera | + 0.41″ |
| 4 |  Constantin Preis | + 0.84″ |
| 5 | Abdelmalik Lahoulou | + 0.88″ |
| 6 |  Hiromu Yamauchi | + 1.09″ |
| 7 |  Wilfried Happio | + 1.23″ |
| 8 |  Jaheel Hyde | + 39.12″ |