Claim: Steffi Graf was ranked No.1 in the world during her career.
Evidence: Stefanie Maria `` Steffi '' Graf -LRB- -LSB- ˈʃtɛfiː ˈgʁa : f -RSB- ; born 14 June 1969 -RRB- is a German former tennis player , who was ranked world No. 1 during her career.