She won 22 Grand Slam titles in a 16-year professional career, the second-most behind Serena Williams (23) since the start of the Open Era in 1968, and the third-most in history behind Margaret Court (24).

Steffi Graf was ranked world No. 1 for 377 weeks, the most of any player – male or female – and won a total of 107 career titles, the third-most in history behind Martina Navratilova (167) and Chris Evert (157).

However, there is one achievement in her career that stands out. In 1988, then-19-year-old Steffi Graf won the Golden Slam, and to today, remains the only player in tennis history – male or female – to achieve the feat.

A term coined by the media, the Golden Slam is when a player wins all four Grand Slams – the Australian Open, French Open, Wimbledon and US Open – in addition to the Olympic gold medal in the same year.

It is as daunting as it sounds and requires great effort and adaptability from a tennis player to triumph across hard courts, grass courts and clay courts, all within months of each other.

Steffi Graf though had those qualities in abundance – she is the only player in history to have won each of the Grand Slams at least four times.

Here’s how Steffi Graf became tennis’ Golden Slam winner in 1988.