They're friends, they've both been ranked No. 1 and now they have became doubles partners for the first time as Serena Williams and Caroline Wozniacki teamed to win a first-round match at the ASB Classic. Williams and Wozniacki overwhelmed Japan's Nao Hibino and Mikoto Ninomiya in a match which was both historic and poignant. The pair jointly have won 24 Grand Slam singles titles _ 23 for Serena _ and 102 WTA singles titles. Williams also has won 23 doubles titles, including 13 Grand Slam and three Olympic titles, mostly with her sister, Venus.