The nine-time champion lost to Argentina’s Diego Schwartzman for the first time in his career, going down 6-2 7-5 as he struggled with his serve. Djokovic also dropped a set and needed more than two hours to defeat 97th-ranked German Dominik Koepfer 6-3 4-6 6-3. The Serb’s temper was on display again. He smashed a racquet after losing a service game, two weeks after being defaulted from the US Open for hitting a line judge with a ball. “It’s not the first nor the last racquet I’ll break in my career,” he said. “That’s how I guess I release sometimes my anger. I am working on my mental and emotional health as much as I’m working on my physical health.” Djokovic will play Norway’s Casper Ruud who earlier battled past Italian fourth seed Matteo Berrettini 4-6 6-3 7-6 (7-5).