Novak Djokovic lost to Mariano Navone in the first round of the US Open on Sunday night. The result marks one of the biggest upsets of the tournament so far and raises immediate questions about Djokovic's form heading into the final Grand Slam of the year.
Navone, ranked 72nd in the world, pulled off the shock result against the legendary Serbian competitor. This wasn't a close match that went five sets either. Djokovic simply did not perform, and Navone capitalized on every opportunity he got.
For Djokovic, the loss comes at a critical moment in his career. He's been chasing history all year, and the US Open represented one of his last realistic chances to add to his Grand Slam total. Instead, he's heading home early.
The tournament loses one of its biggest draws and most reliable deep runs. Without Djokovic in the mix, the men's draw opens up considerably. Other contenders now face a clearer path to the title, though the field remains competitive.
The bigger story here is what this loss says about Djokovic's current level. If he can't get past an opponent ranked outside the top 70, that's a troubling sign for his future at the sport's biggest events.