CINCINNATI, Ohio, Aug 13 (Reuters) - Serena Williams said she "would have lost to anyone" after her 7-5 6-4 defeat by unseeded Austrian Sybille Bammer in the third round of the Cincinnati Open on Thursday.
The world number two, who said she was struggling with a sore throat, made a stack of unforced errors and world number 29 Bammer took full advantage.
"I definitely wasn't as fit as I normally was," Williams said. "I never played worse in my life. It was really a bad match. I think I had about 50 unforced errors.
"I just did not play well at all. I hit balls in the bottom of the net and made so many unforced errors. Anyone could have beaten me today."
After losing a tight first set, Williams was broken twice as she slipped 5-2 behind in the second set.
Only then did she lift her game, getting one of the breaks back and holding for 5-4, but Bammer held her nerve to clinch victory.
It was a doubly bad day for the Williams sisters as Venus also went out at the same stage, beaten 7-6 6-4 by Italian Flavia Pennetta, the 14th-seeded Italian who has now won 14 consecutive matches.
"I saw her after the match and she just said she had made a lot of errors," Serena said of her elder sister. "I was like, wow, I didn't think I would do the same thing, so..."
Bammer said the victory counted as one of the best wins of her career.
"I won against her two years ago, or longer maybe," the 29-year-old said. "I was nervous today, so I don't know how I really played. I just tried to come into the rallies and make her play, and this worked."
Editing by Ian Ransom; To query or comment on this story email firstname.lastname@example.org