PARIS — The first obvious sign of trouble for Novak Djokovic came when he stepped out into Court Philippe Chatrier with a rather large square of beige athletic tape on the back of his neck.
The next indication came on the very first point of his French Open quarterfinal against Pablo Carreño Busta, when Djokovic let a ball toss drop and abandoned his serve mid-motion.
Soon enough, Djokovic was flexing and stretching his left arm or hitting it with his racket. Off to a slow start Wednesday night, Djokovic received massages from a trainer, righted himself and beat Carreño Busta 4-6, 6-2, 6-3, 6-4 to reach the semifinals at Roland Garros for the 10th time.