Alexander Zverev warned for taking picture of ball mark during Madrid Open win

The German was angry that a shot from Alejandro Davidovich Fokina was called in during their third-round match.

Alexander Zverev took a picture of a ball mark after being incensed at a call during his win over Alejandro Davidovich Fokina. Pic: Manu Fernandez/AP

Alexander Zverev was warned for a taking a picture of a ball mark at the Madrid Open as controversy over electronic line calling on clay continued.

The system has become commonplace in recent years on the other surfaces but clay events had largely persisted with line judges and the umpire coming down from his or her chair to examine the mark left by the ball when calls were contested.