Roberto Carballes Baena defeated Holger Rune 6–3, 4–6, 6–3, 6–2 in the first round of the US Open on hard court on 28 August 2023, delivering a significant upset against the pre-match favourite. Rune entered as the heavy favourite with odds of 1.11, while Carballes Baena was priced at 8.09, reflecting expectations that the Danish player would advance comfortably. However, the Spanish competitor executed a composed performance, taking control after a competitive opening set and consolidating his advantage through the third and fourth sets to secure a commanding victory. The result marked a notable early exit for Rune at Flushing Meadows and demonstrated Carballes Baena's capacity to trouble higher-ranked opponents on the hard court stage.