SURFACE: Hard courts.

SITE: USTA Billie Jean King National Tennis Center in New York.

SCHEDULE: The 14-day tournament begins Monday. The women's singles final is Saturday, Sept. 9; the men's singles final is Sunday, Sept. 10.

2016 MEN'S SINGLES CHAMPION: Stan Wawrinka of Switzerland.

2016 WOMEN'S SINGLES CHAMPION: Angelique Kerber of Germany.

LAST YEAR: Wawrinka beat Novak Djokovic 6-7 (1), 6-4, 7-5, 6-3 in the final for his third Grand Slam title. Neither of them is in this year's tournament because of season-ending injuries. Kerber rose to No. 1 in the rankings, ending Serena Williams' 3-year stay there, after collecting her second major championship of the season with a 6-3, 4-6, 6-4 victory over Karolina Pliskova, who had upset Williams in the semifinals. Pliskova is currently ranked No. 1, despite never winning a major title.

MISSING FROM THE FIELD: Players missing from this year's tournament include Wawrinka (left knee surgery), Djokovic (injured right elbow), 2014 runner-up Kei Nishikori (injured right wrist), six-time champion Williams (pregnant), two-time runner-up Victoria Azarenka (child custody dispute) and 2012 French Open runner-up Sara Errani (doping suspension).

BACK IN THE FIELD: Maria Sharapova, the 2006 champion, plays in her first Grand Slam tournament since the 2016 Australian Open. She missed last year's U.S. Open because of a doping suspension and sat out the tournament in 2013 and 2015 because of injuries. Roger Federer returns after skipping the U.S. Open in 2016 while taking off the second half of the year to let his surgically repaired left knee heal.

KEY STATISTIC: 9 -- Number of years since Federer won the last of his five consecutive U.S. Open titles. It's his longest current gap without a championship at any of the Grand Slam tournaments. He won the French Open in 2009, and the Australian Open and Wimbledon this year.

PRIZE MONEY: Total player compensation is a tournament-record $50.4 million. The men's and women's singles champions receive $3.7 million each, up from $3.5 million last year.