Since the introduction of computer rankings on August 23, 1973, a total of 29 players have held the number one spot on the men's world rankings. Of these, as many as 22 have played in Stockholm at some point during their careers, according to the exclusive compilation below, where the world number ones are presented in chronological order.

* Refers only to the number of appearances in the main tournament. For example, Roger Federer lost in the qualifiers in 1999.

Year-end world number ones

19 players have finished the year as world number one (Năstase, Connors, Borg, McEnroe, Lendl, Wilander, Edberg, Courier, Sampras, Agassi, Kuerten, Hewitt, Roddick, Federer, Nadal, Djokovic, Murray, Alcaraz, and Sinner). Of these, 15 have participated in the prestigious ATP tournament, i.e., all except Kuerten, Roddick, Djokovic, and Alcaraz.

World number ones for the longest time

Of the twelve players who have held the world number one ranking for more than 50 weeks, all except Novak Djokovic have played in Stockholm.

Participating world number one

Since the introduction of the computer rankings in 1973, the current world number one has played in the tournament on 14 occasions, as listed below.

1973: Ilie Năstase
1975: Jimmy Connors
1976: Jimmy Connors
1980: Björn Borg
1984: John McEnroe
1988: Mats Wilander
1989: Ivan Lendl
1990: Stefan Edberg
1991: Stefan Edberg
1992: Jim Courier
1993: Pete Sampras
1994: Pete Sampras
1998: Pete Sampras
2002: Lleyton Hewitt*

* The world number one Hewitt was also in the draw for the 2001 tournament but withdrew before his first match due to a back injury.

Unofficial world number ones

Before 1973, there were mainly unofficial rankings compiled by tennis journalists, newspapers, and national federations. Some points-based lists existed for professional players during certain years, but these did not carry the same significance as today's established world rankings.

Before tennis was opened to both professionals and amateurs in 1968, separate lists existed for the different groups. During the three decades leading up to tennis's "opening," the top professional players—with very few exceptions—are considered to have been better than the top amateur players.

In the early years of the computer rankings, there were shortcomings, where some players were regarded as the best in the world at the end of the year without ever reaching the top of the rankings. However, after 1977, there were, in essence, no such disadvantaged players.

During the open era from 1968 onwards, Rod Laver, Ken Rosewall, Stan Smith, Arthur Ashe, and Guillermo Vilas have all been regarded by various prominent tennis experts as the best in the world without being officially ranked as world number one. All five of these tennis icons have played in Stockholm. Notably, Roy Emerson and Fred Stolle do not join this exclusive group. Although the two Australians played in Stockholm and were considered the best among amateurs for much of the 1960s, they fell short in comparison to the top professional players.

Laver, Rosewall, Smith, and Ashe also competed in the tournament in at least one year when they were regarded as world number ones by all or parts of the recognized tennis establishment.

World Number Ones on the Women’s Side

It's not just male world number ones who have played in Stockholm. Both Billie Jean King and Evonne Goolagong Cawley have competed in the tournament. Billie Jean King won the women's singles in the inaugural year of 1969, as well as in the third edition ten years later. Evonne Goolagong Cawley was the second seed in 1975 but was defeated straight away by Swedish hopeful Ingrid Bentzer in straight sets.

King was regarded as the world number one by the unified tennis establishment for extended periods before the introduction of computer rankings on November 3, 1975, while Goolagong Cawley officially held the top spot for two weeks in 1976. Notably, King’s record of 8-0 in matches makes her the player with the most wins without a single loss in the tournament's history.

Summary

The table below provides a summarized overview of the presence of world number ones in Stockholm on the men's side.

* Qualified assessments were made only once a year and not weekly as per the current ranking system. However, it is reasonable to assume that Laver, Rosewall, and Smith were the best in the world for more than 50 weeks, which means that 14 of the 15 players who have been world number ones for the longest time during the open era have played in Stockholm.