Valentin Vacherot upset favourite Lorenzo Musetti 7–6, 7–5 in the second round of the ATP Monte Carlo Masters on clay on 8 April 2026. Despite entering as the clear pre-match favourite at odds of 1.46, Musetti could not convert his advantage against the unseeded Vacherot, who secured both sets in competitive fashion. The Italian's loss represents a significant upset at the prestigious M1000 event, where clay-court form typically favours established players like Musetti. Vacherot's victory suggests improved confidence and consistency on the surface, potentially reshaping their head-to-head dynamic and raising questions about Musetti's early-season clay preparation.