Claim: Steffi Graf won a grand slam in 1988.

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 . Graf won 22 Grand Slam singles titles . Her 22 singles titles put her second on the list of Major wins by a tennis player -LRB- male or female -RRB- since the introduction of the Open Era in 1968 and is third all-time behind Margaret Court -LRB- 24 -RRB- and Serena Williams -LRB- 23 -RRB- . In 1988 , she became the first and only tennis player -LRB- male or female -RRB- to achieve the Golden Slam by winning all four Grand Slam singles titles and the Olympic gold medal in the same calendar year . Furthermore , she is the only tennis player to have won each Grand Slam event at least four times .   Graf was ranked world No. 1 by the Women 's Tennis Association -LRB- WTA -RRB- for a record 377 total weeks -- the longest period for which any player , male or female , has held the number-one ranking since the WTA and the Association of Tennis Professionals began issuing rankings . She won 107 singles titles , which ranks her third on the WTA 's all-time list after Martina Navratilova -LRB- 167 titles -RRB- and Chris Evert -LRB- 157 titles -RRB- . She and Margaret Court are the only players , male or female , to win three grand slams in a calendar year five times -LRB- 1988 , 1989 , 1993 , 1995 and 1996 -RRB- .   Notable features of Graf 's game were her versatility across all playing surfaces , footwork and her powerful forehand drive . Graf won six French Open singles titles -LRB- second to Evert -RRB- , seven Wimbledon singles titles , four Australian Open titles , and five U.S. Open singles titles . She is the only singles player -LRB- male or female -RRB- to have achieved a Grand Slam since hard court was introduced as a surface at the US Open in 1978 . Consequently , Graf 's Grand Slam was achieved on grass , clay , and hard court while the previous five Grand Slams were decided on only grass and clay . Graf reached thirteen consecutive Grand Slam singles finals , from the 1987 French Open through to the 1990 French Open , winning nine of them . She won 5 consecutive Majors -LRB- 1988 Australian Open to 1989 Australian Open -RRB- , and seven Majors out of eight , in two calendar years -LRB- 1988 Australian Open to 1989 US Open , except 1989 French Open -RRB- . She reached a total of 31 Grand Slam singles finals .   Graf is regarded by some to be the greatest female tennis player of all time . Navratilova included Graf on her list of great players . In 1999 Billie Jean King said `` Steffi is definitely the greatest women 's tennis player of all time '' . In December 1999 , Graf was named the greatest female tennis player of the 20th century by a panel of experts assembled by the Associated Press . Tennis writer Steve Flink , in his book The Greatest Tennis Matches of the Twentieth Century , named her as the best female player of the 20th century . In March 2012 , Tennis Channel picked Graf as the greatest female tennis player ever in their list of 100 greatest tennis players of all time .   Graf retired in 1999 while she was ranked World No. 3 . She married former World No. 1 men 's tennis player Andre Agassi in October 2001 . The couple has two children -- Jaden Gil and Jaz Elle . Graf was inducted into the Tennis Hall of Fame in 2004 .