Roger Federer had 12 aces and 35 winners as he breezed past Grega Zemlja.
With boyfriend Rory McIlroy in the stands, Wozniacki fought off a set point in the second to win 6-2, 7-5 on Tuesday.
USTA Billie Jean King National Tennis Center had more personnel at the entry gates, which opened a half-hour earlier.
The US Open got off to a frustrating start Monday as beefed-up security had some waiting up to two hours just to enter the grounds earlier Monday.
The second-seeded Spaniard won 6-4, 6-2, 6-2 in the first round Monday. Nadal, the 2010 champion, skipped last year’s US Open.
The U.S. Open barely got started and one of its most popular players, James Blake, announced his retirement from the game, effective after this US Open.
Venus Williams earned one of her biggest wins since she pulled out of the U.S. Open two years ago because of illness, upsetting 12th-seeded Kirsten Flipkens in the first round Monday.
Nadal’s knees have had recurring problems over the years, particularly the left one, which kept him out from late 2012 until early 2013.
The five-time U.S. Open champion is seeded seventh, the biggest number next to his name at a Grand Slam tournament since 2003.
You spent enough on your tickets for the US Open; enjoy some local ethnic eats along the 7 line that won’t bankrupt you, then head on over to the event.
Murray is seeded No. 3, and the expectation is that he or one of the men ahead of him, Djokovic or Nadal, will hold the trophy.
Obama applauded a USTA initiative to install 5,000 new kid-sized tennis courts across the country and train 15,000 new coaches.
Andy Murray will be the defending champion at a Grand Slam tournament and he suspects he’ll be more nervous than usual.
Sharapova, the 2006 champion at Flushing Meadows, has played only one match on tour since her second-round loss at Wimbledon in June.
The US Open is among the oldest sports competitions in the United States. For all you need to know on getting there, the best food to be found at Arthur Ashe Stadium and ticket packages, check out our guide.