NEW YORK (AP) Serena Williams swung through her service motion with no ball to hit.
Waiting for her injured opponent to return to the court Monday night, Williams climbed out of her chair to keep her arm loose and her mind focused. No matter that the player on the other side of the net was barely chasing after shots. As she seeks the first Grand Slam since Steffi Graf in 1988, the top-ranked American isn't leaving anything to chance.
Her next foe doesn't have the kind of resume to suggest she can challenge Williams, either. Kiki Bertens of the Netherlands is ranked 110th and has advanced past the second round at a major just once. In her previous Grand Slam, she also faced that tournament's defending champion and won just one game against Petra Kvitova at Wimbledon.
Williams and Bertens meet for the first time Wednesday afternoon at Arthur Ashe Stadium as the second round begins at the U.S. Open.
After her first match ended 27 minutes in when 86th-ranked Vitalia Diatchenko retired, Williams mused about why she's ''old school,'' with little interest in taking advantage of the on-court coaching the WTA now allows.
''Maybe it comes from just growing up and just watching so much tennis, just enjoying, you know, Steffi and Monica (Seles), that era where it was just them,'' Williams said. ''They were such mental players. Just looking at that and just being so influenced by that. Thinking one day I'm going to be there. I never thought one day I'm going to be there with my coach or with anything else.''
There's no on-court coaching at the majors. Williams will be out there by herself as she chases history, the ultimate test of mental toughness.
Here are some other things to watch at Day 3 of the U.S. Open:
AMERICAN WOMEN: Venus Williams opens the night session at Ashe against another U.S. player, Irina Falconi. Falconi reached the third round of the U.S. Open in 2011 but hadn't been that far at a major again until this year's French Open. She reached a career-high ranking of 69th this summer and is currently 73rd.
Two more American women, Bethanie Mattek-Sands and CoCo Vandeweghe, meet at Louis Armstrong Stadium. Vandeweghe is seeking her second straight deep run at a major after making the quarterfinals at Wimbledon. The 45th-ranked Vandeweghe beat 29th-seeded American Sloane Stephens in the first round. The 101st-ranked Mattek-Sands, who got in with a wild card, has had less success at her home Grand Slam tournament than the other majors, never advancing past the second round.
The winner could face Serena Williams in the third round.
FISH FAREWELL: American Mardy Fish, who plans to retire after the U.S. Open following years of struggling with anxiety disorder, faces 18th-seeded Feliciano Lopez to open the day at Armstrong.
Fish, a former top-10 player, decided to end his career here to try to make some new memories at Flushing Meadows. In 2012, what should have been one of his best moments turned into the worst, when he withdrew because of a panic attack before his fourth-round match against Roger Federer.
Rafael Nadal also plays Wednesday, facing 74th-ranked Diego Schwartzman of Argentina. No. 1 Novak Djokovic plays 52nd-ranked Andreas Haider-Maurer of Austria to close the night session.