NEW YORK — Day One of the U.S. Open is in the books…well, not exactly. Roger Federer is about to take on Sumit Nagal in the second match of the night session on Arthur Ashe. Barring anything really crazy, we know how that one will end. So we’ll jump the gun and give five thoughts on the rest of the action…

• 20-2 is not a head-to-head; it is a foot-to-butt. But that is the record when Serena Williams plays Maria Sharapova. This latest beatdown came Monday night to kick off the first night session of the 2019 U.S. Open. We’re used to seeing Serena start slowly at majors, beat a few players ranked out of the top 100 and ease her way into the draw. Not this time—when the draw came out, she was immediately locked into this event. She started off against her chief rival, a player she has fought for 15 years now.

Serena looked to be at the peak of her powers, showing no signs fo the back injury that called her to pull out of the Rogers Cup final, barely two weeks ago. She won handedly. Six more matches at this level and she will match another rival, albeit of a different kind: Margaret Court.

•A quick but full stop to note that tennis is awesome. As I am writing this, a 39-year-old from Compton (see below) is beating a 25-year-old from China. Meanwhile, a 16-year-old Californian who weighs 130 lbs. is low-key holding his own again a 37-year-old Italian. (Paolo Lorenzi wound up beating Zach Svadja in five sets.) A seven-footer is putting away a man a full foot shorter. (Reilly Opelka beat Fabio Fognini in four tight sets for one of the biggest wins of his career.) It speaks so well of tennis that it can accommodate such a range of age, physique, origin story and mode of being.

• The men’s defending champion played on Arthur Ashe Stadium today and, as the mystics would say: Djokovic was Djokovic-ing. The world No. 1 doesn’t win with power; he wins by setting glue traps. His offense-defense combo game was in full effect today as he had no problems with Spain’s Roberto Carballes Baena, winning 6-4, 6-1, 6-4. Next up: Argentina’s Juan Londero who upset American Sam Querrey in four sets.

• Little sister was the headliner, but big sister sure sent a message herself. Four years into Senior Tour eligibility, Venus Williams is acquitting herself awfully well in the Main Tour. At 39 years of age and 22 (!) years removed from reaching the finals here for the first time, Venus was simply dazzling today, beating Zheng Saisai 6-1, 6-0 in 67 minutes. It’s only one match, but this was a gem— vintage Venus, a display of power and strategy and poise. Given her play today and her play in Cincinnati earlier this month, she has played herself into …well, if not outright contender status than at least “player-with-a-shot-who-ought-not-to-be-overlooked” status.

• If you think you’ve worked hard this summer, meet Daniil Medvedev. The Russian has logged more matches since Wimbledon than Djokovic, Federer, Nadal and Thiem—the top four seeds—combined. A finalist in Washington D.C. and Montreal, and the winner in Cincy, Medvedev is up to No. 5 in the world. Though the draw did him no favors, the lanky Russian is the best bet in this tournament to crack the Big Three oligopoly. He played his 61st match of the season today to kick off his campaign. But he was efficient, requiring just 84 minutes to beat Prajnesh Gunneswaran of India.