Watch: Tennis player controversially defaulted from his match

“He's obviously said something to someone in the crowd,” commentator Brett Haber said.

“Well, if you can read lips, you know it was colorful words exchanged,” co-commentator Steve Weissman said.

Shapovalov’s action drew a rebuke from the umpire, who called a code violation for unsportsmanlike before an ATP supervisor was sent out onto the court.

Immediately, Shapovalov protested.

“What do you mean, he’s talking to me,” Shapovalov said. “I’m going to tell him off... Give me a code, but don’t call the supervisor.”

Shelton also lobbied on behalf of Shapovalov, saying he heard the chirping coming from the crowd. Ultimately, the pleading fell on deaf ears as Shelton was awarded the match.

“It’s unfortunate that a high-level match like that, such a great match that was highly contested, just an all-out war, ended like that,” Shelton said via The Washington Post. “You never want to see it.”

With the win, Shelton moves on to the DC Open semifinals. Shapovalov, meanwhile, forfeits $53,420 and the 100 ATP rankings points he would have earned for losing outright.