NEW YORK (AP) - Venus Williams takes these tournaments one match at a time. Not a bad plan for a player who's played only one match since Wimbledon.
Williams returned to tennis on the big stage Monday, winning her first match at the U.S. Open after a two-month break she needed to fight off a viral illness.
"A lot of the battle is just trying to be fit and stay healthy," Williams said after her 6-4, 6-3 victory over Vesna Dolonts. "Sometimes I've been losing that battle a lot. But I do feel like I can play six matches. I need to win them. No one is more in one-match-at-a-time mode than me now at this tournament."
Williams, a two-time champion at Flushing Meadows, came into the tournament unseeded for the first time since 1997, when she was 17 and made a run all the way to the final. Of course, people overlook her at their peril. When healthy and motivated, she and her sister, Serena, are the biggest X-factors in any tournament they enter.
Serena opens play Tuesday against Bojana Jovaovski in much the same situation as her sister _ seeded a lowly 28th after missing a big chunk of the year with an injury. But unlike Venus, who had not played a competitive match since Wimbledon, Serena has had a good lead up to the U.S. Open, winning two tournaments earlier this month.
"I think how she's played has been amazing," Venus Williams said. "It was definitely motivating to see her do so well this summer. But I know she can play. She knows she can play tennis. I know I can play tennis, so of course it's great to see those results. But I know I have it in me, also."
In her straight-sets victory over Dolonts, Williams finished with six aces and maxed out her serve at 126 mph. She won on 15 of her 20 trips to the net and added up a 28-7 edge in winners against the travel-weary Russian, who had arrived in New York only four hours before her match _ a victim to travel delays caused by Hurricane Irene.
Venus, who likes to design her own dresses, came out in her version of the traditional "little black dress, tennis-style," replete with lace and zippers on the back.
"Kind of fun," she said.
Joining Serena in first-round action Tuesday will be defending champion and second-seeded Rafael Nadal against Andrey Golubev and both the top seeds _ Novak Djokovic vs. Conor Niland and Caroline Wozniacki vs. Nuria Llagostera Vives.
The only major upset on opening day was Alexandra Dulgheru's 7-6 (3), 6-3 victory over No. 5 Petra Kvitova. Kvitova became the first reigning Wimbledon champion to lose in the first round at the U.S. Open.
She has only won two matches since hoisting the trophy at the All England Club. Asked why she was struggling, she said, "That's a good question, actually."
The player she beat at Wimbledon, Maria Sharapova, had to go three sets Monday for her win. She needed 2 hours, 34 minutes to beat Heather Watson, the remarkably nimble, 102nd-ranked 19-year-old from Britain.
The bad weather stole some practice time over the weekend from Sharapova, a three-time major champion, and she conceded she was far from her best.
"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," she said. "No matter what the situation is, I have the belief."
In the last match of the first day, 16-time major winner Roger Federer beat 54th-ranked Santiago Giraldo of Colombia 6-4, 6-3, 6-2 to collect his 224th victory in Grand Slam play, tying Andre Agassi for second-most in the Open era. Jimmy Connors holds the record at 233.
"It's just another way of saying, 'Roger, you've been doing many things right throughout your career," Federer said. "It gives me good satisfaction and points me in the right direction, I think."
The only men's seed to lose on Day 1 was No. 15 Viktor Troicki of Serbia, a 3-6, 6-3, 4-6, 7-5, 7-5 loser against Alejandro Falla of Colombia.
Other winners included No. 2 Vera Zvonareva, a finalist last year at Wimbledon and the U.S. Open; 16-year-old Madison Keys of Boca Raton, Fla. _ the youngest and, at 455th, lowest-ranked woman in the draw _ who beat 37-year-old Jill Craybas 6-2, 6-4; and No. 12 Agnieszka Radwanska of Poland, who beat her younger sister Urszula 6-2, 6-3.
But surprise 2009 U.S. Open quarterfinalist Melanie Oudin of Marietta, Ga., lost 6-0, 7-6 (7) to Romina Oprandi of Italy, falling to 9-29 in 2011.
Oudin said she'll spend most of the rest of this season playing in lesser events, hoping to get some matches, and wins, under her belt to get some seasoning for a long career in front of her.
The Williams sisters, meanwhile, are thinking about now _ despite what the injury report or the seedings might say.
"We've decided to just enjoy tennis," Venus Williams said. "It's such an honor. We'll do it as long as we can. Right now, the end is not really in sight."