Djokovic stunned in first-round upset at US Open

New York--- Novak Djokovic of Serbia made a shock first-round exit from the US Open tennis championships, falling to Argentina's Mariano Navone in a grueling four-hour-and-36-minute encounter that ended 7-6, 5-7, 4-6, 6-2, 6-1.

The defeat brings a premature close to the 39-year-old Serbian's bid for a record-extending 25th major singles title.

Djokovic, who struggled with physical ailments throughout the match—including episodes of vomiting and compromised serving due to a back complaint—was unable to contain his unseeded opponent, as Navone clinched the biggest victory of his professional career. The loss marks Djokovic's first opening-round defeat at a Grand Slam event since the Australian Open in 2006.

In the women's draw, American Jessica Pegula launched her campaign with a commanding 6-3, 6-2 victory over Romania's Elena-Gabriela Ruse, advancing to the second round while maintaining her aspirations of ascending to the world No. 1 ranking. Italy's Jasmine Paolini also secured her place in the next round, whereas No. 27 seed Barbora Krejčíková bowed out in the opening round.

Ukrainian duo Marta Kostyuk and Elina Svitolina both registered emphatic starts to their tournaments, with Kostyuk dispatching Australia's Storm Hunter 6-4, 6-1, and Svitolina cruising past Argentina's Solana Sierra 6-1, 6-2.