Premise: Stefanie Maria `` Steffi '' Graf ( [ ˈʃtɛfiː ˈgʁa : f ] ; born 14 June 1969 ) is a German former tennis player , who was ranked world No. 1 during her career . Graf won 22 Grand Slam singles titles . In 1988 , she became the first and only tennis player ( male or female ) to achieve the Golden Slam by winning all four Grand Slam singles titles and the Olympic gold medal in the same calendar year . Graf is regarded by some to be the greatest female tennis player of all time . Navratilova included Graf on her list of great players .
Hypothesis: Steffi Graf is not an athlete.
Label: CONTRADICTION