Lorenzo Musetti has been warned for unsportsmanlike conduct for kicking a tennis ball that inadvertently hit a linesperson during his French Open quarterfinal against Frances Tiafoe.

Frances Tiafoe hadn’t dropped a set on the way to the French Open quarterfinals, but he wasn’t up to the task against Lorenzo Musetti.

Lorenzo Musetti advanced to his first semifinals appearance at the French Open Tuesday with a four-set win over Frances Tiafoe. Musetti held off Tiafoe despite receiving an unsportsmanlike conduct warning in the second set after inadvertently hitting a line judge with a ball he kicked toward the back wall at Roland-Garros out of frustration.