After a whiplash 24 hours, the U.S. Open men’s field has opened up in an unexpected way.On Thursday, defending champion Carlos Alcaraz confirmed that he would return to tennis in New York, after four months out with a right wrist injury.Less than 24 hours later, Jannik Sinner — the world No. 1 and dominant men’s player of 2026 in Alcaraz’s enforced absence — withdrew from the fourth Grand Slam of the year with a right knee injury.That’s the opposite of what many fans expected, with Alcaraz not having played any competitive tennis since April; it changes the complexion of a draw that would otherwise have looked like Sinner against the world, the match he has been playing since spring.The Athletic’s tennis team and some fellow aficionados make their case for who is going to emerge as champion in New York City on Sept. 13.Jannik Sinner withdraws from U.S. Open with right knee injuryAva WallaceCarlos AlcarazComing back from four months away, on the back of the injury that tennis players fear most, to defend a title that no man has defended since 2008? That would be beyond absurd.Carlos Alcaraz has been “beyond absurd” so many times in his career to date that his putting the hammer down on the rest of the men’s game to win an eighth Grand Slam title doesn’t seem so far-fetched. Practically, Sinner’s withdrawal increases the likelihood of a Spanish remontada. The early rounds of a Grand Slam, in which five-set tennis offers a buffer against a rusty stanza, are in some ways the ideal environment to play himself into rhythm. And his status as a player returning from injury will act as a counterweight to the pressure of being defending champion.Will opponents try to take advantage of any vulnerability, following the hyperaggressive blueprint that, say, Daniil Medvedev used to defeat a subdued Alcaraz at the BNP Paribas Open in March? They might. But doing that in best-of-five tennis is not the same in doing it in best-of-three, and Alcaraz’s best tennis of 2026 (and his U.S. Open run in 2025) came from his first serve offering both a solid platform and a release valve in tight moments.In so many ways, a title win for him in New York would be remarkable. In so many others, it would just be Alcaraz doing Alcaraz things. That’s why it’s my pick, along with another possibility — but more on that in a second.— James HansenCarlos Alcaraz surged to his second U.S. Open title in 2025. (Sarah Stier / Getty Images)Alcaraz is the man to beat in New York. The 23-year-old Spaniard is returning after four months out with a wrist injury, but Sinner’s withdrawal removes his biggest rival. Before Alexander Zverev won this year’s French Open, Alcaraz and Sinner had shared the previous nine Grand Slam titles.Alcaraz also has proof of dominance at Flushing Meadows. During last year’s title run, he held serve in 98 of 101 service games. The lack of match practice after a long absence is the obvious concern, but Alcaraz has won two of the past four U.S. Opens and, with Sinner out, no player in the field has matched his combination of recent major success and proven results in New York.