Marin Cilic defeated Adrian Mannarino 6–3, 6–2 in the first round of the ATP 250 Hong Kong tournament on hard court on 4 January 2026. Cilic, the pre-match favourite at odds of 1.77, delivered a commanding performance to justify his seeding, breaking down Mannarino's resistance with decisive tennis across both sets. Mannarino, at 2.16 odds, offered limited resistance as Cilic controlled the match with clinical execution. The Croatian's straightforward victory underscores his continued fitness and form heading into the Australian summer, while Mannarino faces an early exit from the tournament.