She found herself at the center of a near-tragedy on 30 April 1993. As then-arch rival Monica Seles was resting during a changeover at the Hamburg Open, a man made his way through the stands, and plunged a knife into her back. At first, it was thought the attack was prompted by the conflict in Seles's Yugoslavia. But it turned out Guenter Parche was a Graf fan, and reasoned that if he took Seles out, Graf would regain the #1 ranking. The attack reverberated across sports. It also changed the course of tennis history. Seles was off the court for 27 months, and never regained her dominating form. Graf visited Seles in the hospital, but didn't comment publicly about the incident until 2004.
Graf retired on 13 August 1999 after beating Martina Hingis at Roland Garros, and losing to Lindsay Davenport at Wimbledon. By this time, she was dating Andre Agassi, whom also won Roland Garros, but was a finalist at Wimbledon that year. With only their mothers as witnesses, they were married on 22 October 2001 at his Las Vegas home. Their son, Jaden Gil, was born four days later. Their daughter, Jaz Elle, was born on 3 October 2003.
Famous for her killer instinct and business-like approach, at times she displayed a sense of humor. During a tight 1995 Wimbledon match against Kimiko Date, she was serving when a fan yelled out "Steffi!" Everyone, including Steffi, burst out laughing. Composing herself, she readied to serve when the fan shouted "Steffi! Will you marry me?" The stadium burst into peals of laughter and play was delayed for a couple of minutes. Steffi readied to serve, tossed the ball, caught it, turned, and yelled to the fan: "How much money do you have?" Graf lost the set, but won the match to face (and defeat) Arantxa Sánchez Vicario for the title.