Alexander Zverev is convinced there was a defect in the electronic line calling system during his Madrid Open win on Sunday after the German risked a hefty fine by pulling out his phone to take a photograph of a contested call.
The top seed overcame Alejandro Davidovich Fokina 2-6 7-6(3) 7-6(0) to reach the last 16 of the claycourt tournament but was frustrated by an incident in the second set when a backhand from his opponent was called in by the tracking technology.
Zverev appealed to chair umpire Mohamed Lahyani to take a look but was rebuffed, and the world number two was then warned for unsportsmanlike conduct after pulling his phone out of his bag and taking a picture of the spot.
"I honestly think there was a defect in the system. There was a mistake in the system in that moment," said Zverev, who later posted the photo on Instagram.
"It's not like one millimeter in, one millimeter out, it was like four-five centimeters. That's why I went to the umpire and said 'Please, come down to have a look at this, I'm not crazy'."
Reuters has contacted the ATP for comment.
Earlier this month, women's world number one Aryna Sabalenka also took a photo of a disputed ball mark during a match in Stuttgart and was warned for unsportsmanlike conduct.
The ATP has adopted the line calling system for all of its tournaments from this year, and while Zverev said he was a fan of the technology he was shocked by the incident in Madrid.
"It's going to be interesting to see what happens now, what kind of fine I'll get, even though I'm right," he said.
"I hope I don't get a fine, because obviously, in my opinion, I'm completely in the right and I should not get fined for this."
