Venus Williams earned one of her biggest wins since she pulled out of the US Open two years ago because of illness, upsetting 12th-seeded Kirsten Flipkens in the first round Monday.
The seven-time Grand Slam champion won 6-1, 6-2 to improve to 15-0 in first-round matches at Flushing Meadows. But with her ranking down to No. 60, she had to open against the Wimbledon semifinalist.
In 2011, Williams withdrew before her second-round match because of Sjogren's syndrome, an autoimmune disease. She was playing just her third event since a first-round loss at the French Open.
"For me, I stay positive because I know I can play great tennis," Williams said. "Sometimes you just have to go through more than what you want to go through. Sometimes you have to have losses. When I had losses, it always motivates me a lot to do better and to work harder."
The 33-year-old looked strong Monday, fighting off three break points at 2-2 in the second set in a game that went to six deuces. Williams was bothered by a lower back injury and played just her third event since a first-round loss at the French Open. She hadn't defeated a top-20 opponent since last October.
"I realize that I haven't had a lot of chances to play this year or a lot of chances to play healthy this year, have had injuries and what have you," she said. "So I'm just going to have to keep working my way into it maybe more than some of the other players. But I know I can do that."
Flipkens had been enjoying a career year. The Belgian had never reached the round of 16 at a major tournament before the Australian Open, then made her run at Wimbledon.
Flipkens was one of two seeded women to lose, along with No. 29 Magdalena Rybarikova of Slovakia.
Venus' sister Serena Williams began her title defense with a 6-0, 6-1 victory, a performance so thoroughly impressive that her opponent, 2010 French Open champion Francesca Schiavone, was prompted in a brief moment of levity to seek comfort by hugging a ball boy. The match lasted exactly an hour, and light rain began falling right after it ended. Eventually, play was called off for the day.
American Sloane Stephens overcame numerous deficits to pull out a 4-6, 6-3, 7-6 (5) victory over Mandy Minella of Luxembourg.
Stephens, seeded 15th, lost the first set to the 110th-ranked Minella and trailed 4-2 in the third, then 3-1 in the final-set tiebreaker.
Stephens won five straight points from there, then closed it out on her third match point to improve to 9-1 in the first rounds of majors.
This was the second time in three years Stephens needed a third-set tiebreaker to win her opening match at Flushing Meadows.
Stephens made her first career Grand Slam semifinal earlier this year at the Australian Open, then followed that by making the fourth round at the French Open and quarterfinals at Wimbledon.
Third-seeded Agnieszka Radwanska also cruised into the second round of the US Open with a 6-1, 6-2 win over Silvia Soler-Espinosa on Monday.
In the tournament's first match at Arthur Ashe Stadium, Radwanska needed only 63 minutes to improve to 28-2 in Grand Slam openers. She won 15 of 21 points at the net.
The US Open is the only major tournament in which the Polish star has never made the quarterfinals. She has reached that stage at the first three Grand Slam events this year, something no other woman has accomplished.
The 69th-ranked Soler-Espinosa, from Spain, advanced to the third round at the US Open the past two years.
Fifth-seeded Li Na advanced in straight sets, defeating Olga Govortsova 6-2, 6-2.
Radwanska withdrew from her last tournament at Cincinnati on Aug. 15 before her quarterfinal against Li to fly home for her grandfather's funeral.
"Sometimes there are some things more important than tennis," Radwanska said. "It was something like that, and it was really a pretty quick choice. Of course, this is the situation that we have to be home for the family, and I think I owed my granddad to be there."
American teen Lauren Davis lost by a "double bagel," falling to 18th-seeded Carla Suarez Navarro of Spain 6-0, 6-0 in 57 minutes.
