Stefanie Maria Graf is a German former professional tennis player. Widely regarded as one of the greatest tennis players of all time, she was ranked world No. 1 in women's singles for a record 377 weeks and won 22 major singles titles, the second-most since the start of the Open Era in 1968 and the third-most of all-time. In 1988, Graf became the first tennis player to achieve the Golden Slam by winning all four major singles titles and the Olympic gold medal in the same calendar year. Furthermore, she is the only tennis player, male or female, to have won each major tournament at least four times.