NEW YORK (AP) Women to watch at the U.S. Open, which begins Monday:

CAROLINE WOZNIACKI

Ranked/Seeded: 1/1

Age: 21

Country: Denmark

2011 Match Record: 53-12

2011 Singles Titles: 6

Career Singles Titles: 18

Major Titles: 0 - Best: F, at U.S. Open in '09

Last 5 U.S. Opens: '10-Lost in Semifinals, '09-F, '08-4th, '07-2nd, '06-Did Not Play

Topspin: Still looking for her first Grand Slam title. ... Coming off disappointing showings at last two major tournaments: She lost in the third round at the French Open and the fourth round at Wimbledon. ... Lost her first two matches of the summer hard-court circuit and brought in someone new - she won't say who it is - to help with coaching. ... Won tour-leading sixth title of year at New Haven on Saturday.

MARIA SHARAPOVA

Ranked/Seeded: 4/3

Age: 24

Country: Russia

2011 Match Record: 39-10

2011 Singles Titles: 2

Career Singles Titles: 24

Major Titles: 3 - Wimbledon ('04), U.S. Open ('06), Australian Open ('08)

Last 5 U.S. Opens: '10-4th, '09-3rd, '08-DNP, '07-3rd, '06-Won Championship

Topspin: Got a boost by winning hard-court tuneup at Cincinnati. ... 11-0 in three-set matches this season. ... Returning to near the top of her game, reached semifinals at French Open, final at Wimbledon this year, but had a lot of trouble with her serve, piling up the double-faults.

PETRA KVITOVA

Ranked/Seeded: 6/5

Age: 21

Country: Czech Republic

2011 Match Record: 45-10

2011 Singles Titles: 4

Career Singles Titles: 5

Major Titles: 1 - Wimbledon ('11)

Last 5 U.S. Opens: '10-3rd, '09-4th, '08-1st, '07-DNP, '06-DNP

Topspin: Tall left-hander's best Grand Slam results have come on grass at Wimbledon, where she reached semifinals last year and won championship this July. ... Real breakthrough season in 2011, collecting four of her five career titles.

LI NA

Ranked/Seeded: 7/6

Age: 29

Country: China

2011 Match Record: 31-13

2011 Singles Titles: 2

Career Singles Titles: 5

Major Titles: 1 - French Open ('11)

Last 5 U.S. Opens: '10-1st, '09-QF, '08-4th, '07-DNP, '06-4th

Topspin: At the French Open this month, became the first tennis player from China - man or woman - to win a Grand Slam singles title. ... After that tournament ended, though, she won only three of her next seven matches. ... Her powerful, flat groundstrokes should be effective on the hard courts at the U.S. Open.

SERENA WILLIAMS

Ranked/Seeded: 29/28

Age: 29

Country: United States

2011 Match Record: 16-2

2011 Singles Titles: 2

Career Singles Titles: 39

Major Titles: 13 - Wimbledon ('02, '03, '09, '10), U.S. Open ('99, '02, '08), Australian Open ('03, '05, '07, '09, '10), French Open ('02)

Last 5 U.S. Opens: '10-DNP, '09-SF, '08-W, '07-QF, '06-4th

Topspin: Returns to New York after missing last year's U.S. Open. ... Could face No. 4 Victoria Azarenka in third round. ... Shortly after winning Wimbledon in 2010, cut her foot on glass, leading to a series of health issues, including clots in her lungs. ... Returned to the tour in June. ... Won hard-court tournaments at Stanford and Toronto this month, her first back-to-back titles since 2008. ... She's 44-0 in first-round matches at major tournaments.

VENUS WILLIAMS

Ranked/Seeded: 36/Unseeded

Age: 31

Country: United States

2011 Match Record: 7-3

2011 Singles Titles: 0

Career Singles Titles: 43

Major Titles: 7 - Wimbledon ('00, '01, '05, '07, '08), U.S. Open ('00, '01)

Last 5 U.S. Opens: '10-SF, '09-4th, '08-QF, '07-SF, '06-DNP

Topspin: Like younger sister Serena, returned to the tour in June. Had been sidelined since injuring her hip at the Australian Open in January. ... 59-10 career record at U.S. Open, but hasn't won the championship in a decade.