Jack Sock has never made it past the third round of a Grand Slam tournament, and the 2018 French Open isn't going to buck the trend for the American who hails from Overland Park, Kan., and played his college tennis at Nebraska. In his first-round loss to Jurgen Zopp, Sock's 2018 struggles continued. He hasn't had back-to-back wins this season, and in addition to playing against Zopp, Sock found himself competing with the match's chair umpire as well.

Sock lost to Zopp 6-7, 6-2, 4-6, 7-6, 6-3; but the No. 14 seed was trading barbs with chair umpire Paula Vieira Sousa throughout the match.

At one point, Vieira Sousa was showing Sock where a ball hit while he stood feet from her, repeating that the ball "was not close to the line." Later on, after Vieira Sousa stopped play to check on a ruling, Sock turned away muttering "that makes no sense."

Things came to a head when Sock asked for a new referee of the match.

Sock: "If I could request a new one, I would. Shocking stuff. Could I request a new ref?

Vieira Sousa: "For what?"

Sock: "For you. You're atrocious."

After the match, Sock wasn't apologetic about his behavior, saying "if she does her job, then I wouldn't have to do that," per Stuart Fraser.

This loss marks Sock's third straight first-round exit at a Grand Slam. After being ranked No. 8 as recently as November, he may see his slide continue after another disappointing early exit. He is now 5-11 this season.