After Serena Williams beat her sister Venus, talk at the U.S. Open turned to who might be able to derail Serena's Grand Slam quest.
The quick, easy — and likely correct — answer was: nobody.
The leading candidates seemed to be Petra Kvitova of the Czech Republic, a two-time Wimbledon champion, and Victoria Azarenka of Belarus, a two-time Australian Open champion and twice a loser in the finals here to Williams.
Then, in their quarterfinals Wednesday, the leading candidates lost.
Kvitova, with a big left-handed serve and deep strokes that seemed a threat to Williams, faded badly in a third set and lost to Flavia Pennetta of Italy, 4-6, 6-4,...