'You can't win a Grand Slam and not be really, really, really, really, really good. I have a lot of things that I need to focus on and do to get ready.'
Serena Williams continues her push for a record-equalling 24th Grand Slam trophy when she takes on Sloane Stephens on Saturday in an all-American clash of former US Open champions.
Williams has blitzed through the draw without dropping a set but faces a tricky third-round test against the 26th-seeded Stephens, whose run to the 2017 US Open title propelled her to a career-high ranking of No. 3.
Stephens, 27, has struggled to kick on, however, and has not reached a tournament final since the WTA Finals in 2018.
Stephens, who has slipped to No. 39 in the world, entered the second Grand Slam of the year with a miserable 1-7 record but Williams still expects a stern challenge.
"Well, she's a great competitor. It's an incredibly interesting match, because she's actually a US Open champion," said Serena, who defeated Kristie Ahn and Margarita Gasparyan en route to the third round.
"You can't win a Grand Slam and not be really, really, really, really, really good. I have a lot of things that I need to focus on and do to get ready."
Williams, 38, has defeated her compatriot in four straight matches since a defeat in the quarter-finals of the 2013 Australian Open.
In other matches, former world number one Victoria Azarenka plays Iga Swiatek, second seed Sophia Kenin meets Ons Jabeur and seventh seed Madison Keys clashes with Alize Cornet.
In the men's draw, third seed Daniil Medvedev's bid for a maiden Grand Slam continues when he faces local hope JJ Wolf, while 2014 champion Marin Cilic takes on second seed Dominic Thiem in the highlight of the third-round matches.
Felix Auger-Aliassime, who defeated Andy Murray and has not dropped serve in the tournament so far, faces unseeded Frenchman Corentin Moutet.
Factbox: Sloane Stephens v Serena Williams
WTA ranking: 39 (Highest ranking: 3)
Grand Slam titles: 1
WTA career titles: 6
2019 US Open performance: First round
Best US Open performance: Champion (2017)
Stephens is looking to recapture the form that propelled her to the title in 2017. She registered straight-sets victories over Mihaela Buzarnescu and Olga Govortsova, dropping just 10 games en route to the third round.
Stephens has beaten Williams just once in six meetings, at the Australian Open in 2013.
WTA ranking: 8 (Highest ranking: 1)
Grand Slam titles: 23
WTA career titles: 73
2019 US Open performance: Runner-up
Best US Open performance: Champion (1999, 2002, 2008, 2012, 2013, 2014)
Williams is a six-times US Open champion but has not triumphed at Flushing Meadows since 2014.
The 38-year-old has not lost a third-round match at the US Open since her maiden appearance in 1998, and she will hope to keep that run going when she faces Stephens, whom she has defeated in four successive meetings.
Williams, who defeated Kristie Ahn and Margarita Gasparyan in straight sets in the first two rounds, is chasing a 24th Grand Slam crown, which would draw her level with Margaret Court.
HEAD TO HEAD: Williams leads 5-1
2015 Williams def. Stephens 1-6 7-5 6-3 (French Open, Outdoor Clay)
2015 Williams def. Stephens 6-4 6-0 (Madrid, Outdoor Clay)
2015 Williams def. Stephens 6-7(3) 6-2 6-2 (Indian Wells, Outdoor Hard)
2013 Williams def. Stephens 6-4 6-1 (U.S. Open, Outdoor Hard)
2013 Stephens def. Williams 3-6 7-5 6-4 (Australian Open, Outdoor Hard)
2013 Williams def. Stephens 6-4 6-3 (Brisbane, Outdoor Hard)