In baseball, a grand slam is a home run with the bases loaded and it counts for four runs. In tennis, a Grand Slam is winning the four most important tournaments--the Australian and French Opens, Wimbledon, and the U.S. Open--in one year. While many baseball players hit grand slams, only five players have ever won the Grand Slam in tennis. One of those players is Steffi Graf, who pulled off this feat in 1988. During her career, Graf has been the best women's tennis player in the world, twice spending long periods of time as the game's top-ranked player.

Graf is always in excellent condition, trains and practices very hard, and is one of the world's fastest players. She has a powerful serve and effective backhand, but her biggest weapon is her forehand. "Her forehand puts fear in everybody," pro player Zina Garrison told Sports Illustrated. Her forehand...