It seems that Serena Williams has been thrilling tennis fans with her fantastic play for a long time, but only recently have people begun to truly appreciate the greatness of this incredible athlete. With more than twenty Grand Slam titles to her name, Serena is beginning to earn the reputation among many fans and commentators as the greatest tennis champion of all time, male or female. In 2015, she completed the so-called Serena Slam for the second time in her career, winning all four Grand Slam tennis tournaments (Wimbledon, the U.S. Open, the Australian Open, and the French Open) in a row.