The ATP Rankings are the Association of Tennis Professionals' (ATP) merit-based method for determining the rankings in men's tennis. The top-ranked player is the player who, over the previous 52 weeks, has garnered the most ATP-ranking points. Points are awarded based on how far a player advances in tournaments and the category of those tournaments. The ATP has used a computerized system for determining the rankings since August 23, 1973. Starting in 1979, an updated rankings list is released at the beginning of each week.
Since the introduction rankings the method used to calculate a player's ranking points has changed several times. As of 2011, the rankings are calculated by totaling the points a player wins in his best eighteen tournaments, subject to certain restrictions. For top players the counting tournaments are the four Grand Slam tournaments, the eight mandatory ATP World Tour Masters 1000 tournaments, the player's best four eligible ATP World Tour 500 series tournaments (the non-mandatory ATP Masters 1000 event in Monte Carlo may be substituted for one of these), and his best two results from ATP World Tour 250 series. Lower-ranked players who are not eligible for some or all of the top tournaments may include additional ATP 500 and ATP 250 events, and also ATP Challenger Series, and Futures Series tournaments. Players who qualify for the year-end ATP Finals also include any points gained at that tournament in their total, increasing the number of tournaments they may count to 19.
Roger Federer holds the records for both the most total weeks at No. 1 (310) and most consecutive weeks at No. 1 (237).Pete Sampras holds the record for the most year-end No. 1 rankings (six, all consecutive).Patrick Rafter spent the least time at No. 1 (one week).
Lleyton Hewitt is both the youngest world No. 1 (20 years, 268 days) and youngest year-end No. 1, while Roger Federer is the oldest No. 1 (36 years, 314 days).Novak Djokovic is the oldest year-end No. 1 (31 years, 223 days).
Roger Federer is the player with the longest time span between first and most recent dates at world No. 1 in the history of the ATP. He most recently held the top ranking the week of June 18, 2018, more than fourteen years after first becoming No. 1 on February 2, 2004.
Rafael Nadal has the longest timespan, 9 years, between his first and last year-end No. 1 titles, 2008 and 2017.
Two players, Ivan Lendl and Marcelo Ríos, have reached No. 1 without previously having won a Grand Slam tournament. Lendl reached No. 1 on February 21, 1983, but did not win his first Grand Slam title until the 1984 French Open. Ríos reached No. 1 on March 30, 1998, but retired without ever having won a Grand Slam singles title, making him the only No. 1 player with that distinction.
Since 1973 when the ATP rankings started, there have been twelve years in which one player held the top spot for the entire year: Jimmy Connors in 1975, 1976, and 1978; Ivan Lendl in 1986 and 1987; Pete Sampras in 1994 and 1997; Lleyton Hewitt in 2002; Roger Federer in 2005, 2006, and 2007; and Novak Djokovic in 2015. In contrast to this, 1999 saw five different players hold the No. 1 ranking (the most in any single year): Pete Sampras, Carlos Moya, Yevgeny Kafelnikov, Andre Agassi, and Patrick Rafter.
John McEnroe held the No. 1 ranking on a record 14 different occasions, and Pete Sampras is the only other player to have held it on 10 or more occasions with 11 different stints.
The statistics are updated only when the ATP website revises its rankings (usually every Monday morning except when tournament finals are postponed).
Roger Federer has spent a total of 310 weeks at world No. 1, including 237 consecutive weeks at the top of the ATP rankings, the most of any player. Federer is also the player with the longest time span between first and most recent dates as world No. 1.
Ilie Năstase became the first ATP world No. 1 ranked player on August 23, 1973.
Pete Sampras spent a total of 286 weeks at the top of the ATP rankings and holds the record of six consecutive years ended as world No. 1.
The ATP year-end No. 1 ranked player is determined as the player at the head of the ATP rankings following the completion of the final tournament of the calendar year, usually in November or December. Pete Sampras holds the record of six year-end No. 1 rankings, which were in consecutive years from 1993 through 1998.
Six players have stayed at ATP No. 1 in the rankings every week of a calendar year. Roger Federer is the only player to have been ranked No. 1 every week for three consecutive calendar years.
^ abcdefghi"Hewitt jubilant as world's No. 1". The Age. November 15, 2002. Retrieved September 6, 2012. Only five other players – Stefan Edberg (1990–91), Ivan Lendl (1985–87), John McEnroe (1981–84), Bjorn Borg (1979–80) and Jimmy Connors (1974–78) – have achieved the mighty feat.
^ abcFord, Bonnie D. (April 9, 2010). "Tennis still imbued in Lendl's blood". ESPN. ESPN Internet Ventures. Retrieved September 6, 2012. In 1988, [Wilander] won a five-set endurance contest, breaking a six-match losing streak to Lendl. The win interrupted Lendl's three-year reign as world No. 1...
^Wilansky, Matt (August 31, 2006). "Inside the numbers". ESPN. ESPN Internet Ventures. Retrieved September 5, 2012. [I]n 1999 he won the French Open title, the only Major that had eluded him. He finished the year ranked No. 1 in the world for the first and only time in his career.