Carlos Alcaraz’s wrist injury recovery and extended absence since his April 2026 Barcelona Open match create the central uncertainty for his U.S. Open title defense, with the world No. 2 on the entry list yet sidelined from all lead-up events including Cincinnati. Recent intense practice sessions and medical confirmation of healing support a possible return, but the complete lack of competitive sets leaves questions about match fitness, rust, and re-injury risk heading into the late-August Grand Slam. The closely balanced 54.5% implied probability reflects this tension, as traders weigh positive training updates against expert cautions and the absence of tune-up confirmation at events like Winston-Salem. Further positive fitness reports or an official pre-tournament commitment could strengthen Yes positioning, while any setback or explicit withdrawal signal would likely shift sentiment the other way.