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 . She won 107 singles titles , which ranks her third on the WTA 's all-time list after Martina Navratilova ( 167 titles ) and Chris Evert ( 157 titles ) . Graf is regarded by some to be the greatest female tennis player of all time .
Hypothesis: Steffi Graf is not an athlete.
Label: CONTRADICTION