Steffi Graf completed a calendar-year Golden Slam after winning the 1988 US Open.
Graf defeated Gabriela Sabatini in the US Open final, 6–3, 3–6, 6–1. That victory completed her sweep of all four major singles titles in 1988: the Australian Open, French Open, Wimbledon and US Open. She then won the Olympic gold medal in Seoul, adding the fifth achievement required for a Golden Slam.
The term “calendar-year Golden Slam” means winning all four majors and Olympic singles gold in the same calendar year. Graf remains the only singles player to accomplish it, making the feat one of tennis’s defining records.
The US Open was also Graf’s first title at the tournament and her fifth major singles championship overall. Her opponent, Sabatini, was playing in her first major final. Martina Navratilova, one of the wrong options, was the defending champion but lost in the quarterfinals.