NEW YORK — Trailing big in the first round of the U.S. Open, Maria Sharapova thought — well, no, she was certain — that she'd pull through if she could push her inexperienced opponent to a third set.
And Sharapova was right.
Shrieking as loudly as ever, Sharapova came back from a set and a break down against 19-year-old Heather Watson of Britain to win 3-6, 7-5, 6-3 on Monday, improving to 12-0 this year in matches that went the distance.
"It's just a matter of belief within myself, that no matter how well or bad or good I'm playing, or my opponent is playing, I know I can tough it out," the No. 3-seeded Sharapova said after her 2½-hour victory. "No matter what the situation is, I have the belief."
And why not? Sharapova won six Grand Slam matches at Wimbledon alone this summer, reaching the final there before losing to Petra Kvitova. Fresh off that triumph, Kvitova — a 21-year-old from the Czech Republic seeded No. 5 now — failed to follow it up, flopping at the U.S. Open with a 7-6 (7-3), 6-3 loss to 48th-ranked Alexandra Dulgheru of Romania.
Kvitova is the first reigning Wimbledon women's champion to lose her first match at the U.S. Open in the same year.
"This is something new for me," Kvitova said about her new status as Grand Slam champion. "I've felt a little pressure."
She was the only seeded woman to exit on Day 1 of the year's last major tournament, joined on the way out by No. 15 Viktor Troicki, a 3-6, 6-3, 4-6, 7-5, 7-5 loser to Alejandro Falla.
At night, 2000-01 U.S. Open champion Venus Williams played her first match in two months and beat 91st-ranked Vesna Dolonts 6-4, 6-3. Williams hit six aces and 28 total winners against the weary Dolonts, who left Moscow at 4 a.m. Eastern and arrived at the Billie Jean King National Tennis Center at 4 p.m., after having flights canceled Saturday and Sunday because of Tropical Storm Irene.
And No. 3 Roger Federer tied Andre Agassi for the second-most Grand Slam wins in the Open era by ousting Santiago Giraldo 6-4, 6-3, 6-2. Federer, who turned 30 this month, has 224 Grand Slam wins, nine behind Jimmy Connors.
Early winners included No. 8 Mardy Fish, a former Tampa resident who beat Tobias Kamke 6-2, 6-2, 6-1; No. 9 Tomas Berdych and No. 13 Richard Gasquet.
Advancing with Sharapova to the second round were No. 2 Vera Zvonareva, a finalist last year at Wimbledon and the U.S. Open, and No. 12 Agnieszka Radwanska, who beat her younger sister Urszula Radwanska 6-2, 6-3.
Boca Raton's Madison Keys, 16 — the youngest and, at 455th, lowest-ranked woman in the draw — beat 37-year-old former Gator star Jill Craybas 6-2, 6-4.
American Melanie Oudin, a surprise 2009 U.S. Open quarterfinalist, lost 6-0, 7-6 (9-7) to Romina Oprandi of Italy.