It’s as if winning streaks are a prerequisite if you’re going to be at the top of the rankings. Novak Djokovic won dozens of matches in a row last year, and in 2012, Victoria Azarenka is unbeaten.

In women’s doubles, the world’s number-one pair of Liezel Huber and Lisa Raymond is racking up the victories. The Americans are in the semifinals at this week’s tournament in Indian Wells, Calif., bringing their winning streak in ’12 to 15.