TENNIS-AUS-OPEN

Serena Williams of the US plays a shot during a training session on day twelve of the 2015 Australian Open tennis tournament in Melbourne on January 30, 2015, ahead of the women's singles final on January 31. The bitter rivalry between Australian Open finalists Serena Williams and Maria Sharapova took root on the hallowed Wimbledon turf in 2004 and is still thriving more than a decade later -- both on and off the court. Sharapova was a 17-year-old unknown when she stunned the tennis world by winning at the All England club in 2004, going on to become a superstar with five Grand Slams who ranks as the world's highest paid female athlete. AFP PHOTO / WILLIAM WEST-- IMAGE RESTRICTED TO EDITORIAL USE - STRICTLY NO COMMERCIAL USE (Photo credit should read WILLIAM WEST/AFP via Getty Images)