Steffi Graf is a German former professional tennis player widely regarded as one of the greatest in history. She was ranked world No. 1 for a record 377 total weeks, the longest period for which any player has held the top-ranking. Graf won 22 Grand Slam singles titles, the third-most since the beginning of the Open Era. In 1988, she became the only tennis player to achieve the Golden Slam by winning all four Grand Slam singles titles and the Olympic gold medal in the same calendar year.