MASON, Ohio (AP) -- Serena Williams dropped out of the Western & Southern Open because of a sore toe Wednesday, her latest setback after nearly a year away from the court.
Her decision to rest her troublesome right foot cost the women's bracket yet another high-profile player and raised doubts about her readiness for the U.S. Open.
"I don't think this is a good time for me to take a big chance,'' she said, after the big toe on her right foot bothered her during a morning workout. "I just don't think that would be smart.''
She was the latest high-profile woman to drop out of the Cincinnati-area tournament, which combined a women's event and the men's Masters for the first time this season.
Sister Venus Williams withdrew before the start because of a virus that also forced her to sit out the tournament in Toronto. Defending champion Kim Clijsters couldn't play because of an injured abdomen.
The tournament also lost top-ranked Caroline Wozniacki on Wednesday afternoon. Wozniacki dropped her opening match for the second consecutive week, falling to American Christina McHale 6-4, 7-5 in the second round. Third-seeded Victoria Azarenka withdrew before her evening match because of a strained right hand.
In the men's bracket, top-ranked Novak Djokovic beat American Ryan Harrison 6-2, 6-3. No. 2 Rafael Nadal beat French qualifier Julien Benneteau 6-4, 7-5 while playing with two fingers on his right hand bandaged to protect burned fingertips. The left-handed Nadal said he got the burns by touching a hot plate at a local restaurant.
Serena Williams' withdrawal was unexpected. She had won two straight tournaments at Stanford and Toronto, gaining some momentum after missing nearly a year because of medical problems. Williams arrived looking to win three tournaments in a row for the first time since the start of the 2008 season.
She beat Lucie Hradecka in two sets on Tuesday night, when the toe started bothering her. It was her seventh match in eight days and her 12th straight win, equaling the longest such streak on the WTA Tour this year.
The toe was worse when she woke up on Wednesday - sore and a little swollen. She talked to her father and her sister before deciding to withdraw from the tournament. It's the same foot she cut on glass at a restaurant and had two operations.
"It's not as bad as it was before,'' she said. ``It's just a lot of match play. I've been playing a lot of the matches, more than I have in a long time, and also training as well. It got a little aggravated. Instead of making it worse, I've decided it will be in my best health not to go on.''
The time off also will give her the opportunity to attend the wedding Kim Kardashian, who is marrying NBA player Kris Humphries in California over the weekend. Williams is a friend of the reality TV star.
"Now that I have time, I probably will,'' she said. ``I hadn't thought about it.''
After a news conference to announce her decision, Williams headed across Interstate 71 to enjoy a ride at Kings Island. The amusement park released a photo of her in the front row of its Diamondback roller coaster, holding back her hair at the start of a drop.
While Williams was deciding to withdraw, Wozniacki was struggling to keep the ball in play. She also lost her opening match last week in Toronto.
The Dane had never faced the 76th-ranked McHale, who broke Wozniacki in the 11th game of the second set with a delicate drop shot. She clinched the match when Wozniacki sailed a forehand long.
"I can't remember the last time I had two first-round exits,'' she said. ``It's a bit different. You know, I usually play better as the week goes on, but what happens, happens.''
Djokovic has been the world's most consistent player this season, going 54-1. Last week in Montreal, he became the first to win five ATP Masters series titles in one season. He improved to 30-0 on hard courts by taking advantage of Harrison, a 19-year-old from Florida who broke his serve to open the match, then fell apart. Harrison had 20 unforced errors in the first set alone.
Djokovic would like to keep his winning streak intact heading into the U.S. Open, where he lost the title match to Nadal last year.
"Performing the best tennis is the priority in New York,'' he said. ``But I'm not playing the matches in this tournament just to get some practice. I'm playing to win.''
Nadal played with the index and middle fingers on his right hand taped. It bothered him on his backhand shots.
"I got burned,'' he said. ``I had a little bit of an accident in a restaurant a few days ago.''
Freelance writer Mark Schmetzer in Mason contributed to this report.