When tennis players claim they don’t look at the draw sheet of a tournament, it is often a cover. They just want to avoid talking about possible future opponents.

Other times they genuinely don’t want to know what lies ahead, preferring instead to focus on only the one match in front of them. And sometimes, they just have it wrong.

Consider Diego Schwartzman, an expert service returner who upset No. 6 Alexander Zverev, 3-6, 6-2, 6-4, 6-3, on Monday to reach the United States Open quarterfinals for the second time. After the match, the television commentator Brad Gilbert interviewed Schwartzman on the court and noted that his next opponent would be either Rafael Nadal or Marin Cilic.

“Oh,” Schwartzman replied with a laugh. “I thought I was playing Berrettini.”

It was a charming moment of candor from Schwartzman, the No. 20 seed. He had assumed that because the video screen inside Arthur Ashe Stadium during his match kept showing highlights and scores from No. 24 Matteo Berrettini’s 6-1, 6-4, 7-6 (6) victory over Andrey Rublev in nearby Louis Armstrong Stadium, that the winner of that match would be his next foe.