AP - Serena Williams entered Tuesday with a 37-0 record in the first round at Grand Slam tournaments. She also began the day with a four-match losing streak, the longest of her career. Williams focused on the second of those statistics, the more discouraging one. And while she never appeared truly in danger of coming out on the wrong end against 100th-ranked Klara Zakopalova, there were times when it did seem Williams simply could not wrap things up.More...