Four Top-Ten Seeds Lose

On Tuesday, No. 4. Dominic Thiem, No. 8 Stefanos Tsitsipas, No. 9 Karen Khachanov and No. 10 Roberto Bautista Agut were knocked out of the Open in the first round. Thiem bowed out in four sets, falling, 6-4, 3-6, 6-3, 6-2, to 87th-ranked Thomas Fabbiano of Italy in Arthur Ashe Stadium. Tsitsipas also lost in four sets to the in-form Andrey Rublev, a 43rd-ranked Russian who defeated Federer at the Cincinnati Masters this month. Bautista, who was the non-Big Three semifinalist at Wimbledon this year, lost in five sets to 47th-ranked Mikhail Kukushkin of Kazakhstan. Khachanov fell in five sets to the 216th-ranked Vasek Pospisil.

Serena Williams Defeats Caty McNally

Caty McNally made it clear very quickly that Williams, a 23-time Grand Slam singles champion, was in for a serious challenge on Wednesday. “I felt really good out there on the big stage; I wasn’t too nervous,” McNally, a 17-year-old American, said. As Christopher Clarey writes: “It was a classic Williams performance. She has turned so many tricky matches her way through the decades: first against her elders and now against new arrivals not even half her age.”

Top-Seeded Naomi Osaka Advances

Osaka battled her nerves in a three-set, first-round win on Tuesday. Two days later, Osaka, who is wearing a brace on her injured left knee, shook out her leg several times because of apparent discomfort. Playing in front of a star-studded support box that included Kobe Bryant and Colin Kaepernick, she advanced to the third round with a 6-2, 6-4 win over Magda Linette, who won the Bronx Open last week. Osaka awaits either Timea Babos or the teenage phenom Coco Gauff in the third round.

Pop Quiz: U.S. Open Edition

We know our readers are avid sports fans. So we’re going to start putting you to the test. This week, see if you know the answer to this question, from Ben Rothenberg.

Denis Kudla will play a third consecutive Serbian opponent when he faces Novak Djokovic on Friday. Venus Williams beat two Serbs in a row on her way to the 2007 semifinals. Who were they?

Last week’s correct answer? The winning quarterback of the X.F.L. championship at the end of its only season in 2001 was Tommy Maddox. The first reader to answer correctly was Jonathan Jacoby, who sent the answer in two minutes flat. We salute you.

Email your answer to sportsnewsletter@nytimes.com. First person to send in the correct answer gets a shout-out next week.