Possible Clues:

• Graf rival, once
• Two-time U.S. Open winner Monica
• Yugoslavian-born winner of nine Grand Slam tournaments
• Graf's court rival
• Monica who won nine tennis majors
• Monica ___, two-time U.S. Open champ
• 1990s tennis champ with nine Grand Slam titles
• Athlete who refused to play in Germany after 1993
• Nine-time Grand Slam singles champ
• Tennis star with a palindromic name