“They just liked the name,” he said, “they thought it was cool.”

Sandgren avoided getting teased much growing up — “There aren’t any good jokes. What are they going to call me, Tennys ball?” — but his name did come with a certain amount of pressure for a tennis player.

“I feel like I had to play decent,” Sandgren said, “I had to be decent, I couldn’t be bad. I had to at least not be terrible, that was the goal.”

Sandgren advanced Wednesday to play the 23-year-old German Wunderkind when his second-round opponent, the talented and controversial Australian Nick Kyrgios retired with pain in his right shoulder while trailing Sandgren, 6-3, 3-0, on Wednesday. A day earlier, Sandgren recorded his first career ATP win at Rock Creek Tennis Center.

Sandgren is almost never up against players of Zverev’s caliber; he usually toils away at challenger-level events. He played two years at Tennessee and turned pro in 2011. Since then, he has made just less than $375,000 playing singles and doubles combined, and reached his career-best ranking — 100th in the world — in June.

By comparison, Kyrgios has made just north of $4.5 million in combined singles and doubles prize money and Zverev has amassed about $4.1 million, and both turned pro two years after Sandgren.

“I wish him the best,” Sandgren said after Kyrgios retired. “He pays the bills for me, what he builds for the game only helps me. So I wish him the best.”

As the unexpected spoiler on Wednesday, Sandgren did throw a bit of chaos into the Citi Open bracket, evidenced by a hallway scene outside the stadium court just after the match, before Sandgren arrived to speak to reporters.

That was when a shirtless Zverev, who had finished his match a few hours earlier, emerged from what appeared to be post-match treatment and sidled up to Citi Open tournament director Keely O’Brien. Zverev had been scheduled to play on stadium court, the event’s main stage, on Thursday with the assumption that Kyrgios would be his opponent.

He wanted to make sure he wouldn’t be bumped to a lower court due to the upset.

“He’s an American!” Zverev said, placing a lanky arm around O’Brien’s shoulder. “Besides, people know his name.”

The match was moved to Grandstand 1 all the same following a three-hour rain delay.