Caroline Wozniacki could not overcome a right knee injury or the play of 96th-ranked Romanian Irina-Camelia Begu. (Bill Kostroun/Reuters)

But during that span, the 22-year-old Dane failed to reach a single Grand Slam final. Now those major struggles have finally caught up to her.

Wozniacki crashed out of the U.S. Open on Tuesday in a first-round loss to unseeded and 96th-ranked Irina-Camelia Begu of Romania, 6-2, 6-2.

Earlier in the day, 19-year-old American Sloane Stephens upset Italian Francesca Schiavone, the No. 22 seed, 6-3, 6-4, to set up a second-round contest against German Tatjana Malek. Stephens has advanced to at least the third round of three of her last four majors.

Other seeded women to fall Tuesday included 20-year-old American Christina McHale (No. 21), Klara Zakopalava of the Czech Republic (24), Romanian Monica Niculescu (26), Austrian Tamara Paszek (29) and Shuai Peng of China (32).

American teen Sloane Stephens is into the second round. (Alex Trautwig/GETTY IMAGES)

“You always want to go in and do your best no matter what’s happening out there,” Wozniacki said after the match. “I tried. I didn’t succeed. I didn’t play particularly well, made too many errors.

“It’s unfortunate because it’s a huge tournament, a tournament you want to play well in.”

Poor play at the huge tournaments has been Wozniacki’s Achilles’ heel since she ascended to the top tier of the women’s game. She made a pair of Grand Slam semifinals in 2011 — the second at Flushing Meadows — but she has still never won a major and has not reached a final since the 2009 U.S. Open. Wozniacki lost her first-round match at Wimbledon to Paszek.

Wozniacki, who is dating Irish Scottish golfer Rory McIlroy, will release her own underwear line called “This is Me” next month. But unlike Maria Sharapova, whose new “Sugarpova” candy line release hasn’t slowed her on-court performance, Wozniacki could be better-suited to focus on returning to health and returning to the form that earned her the world’s No. 1 ranking.

Follow us: @MattBrooksWP | @CindyBoren


Men’s scoreboard | Women’s scoreboard

Serena Williams cruises in first-round match

U.S. Open is Andy Murray’s challenging moment for a breakthrough

Brian Baker’s long road back to Flushing Meadows

Wozniacki’s match put on hold by opponent’s ringing cell phone