Title: List of ATP number 1 ranked singles tennis players
Content:  The ATP Rankings are the Association of Tennis Professionals' (ATP) merit-based system 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 ranking points on the ATP Tour. 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 1973, 26 men have been ranked No. 1 by the ATP, of which 17 have been year-end No. 1. The current world number one is Novak Djokovic from Serbia.
Title: List of WTA number 1 ranked singles tennis players
Content:   The WTA Rankings are the Women's Tennis Association's (WTA) merit-based system for determining the rankings in women's tennis. The top-ranked player is the player who, over the previous 52 weeks, has garnered the most ranking points on the WTA Tour. Points are awarded based on how far a player advances in tournaments and the category of those tournaments. The WTA has used a computerized system for determining the rankings since November 3, 1975. Since 1975, 27 women have been ranked No. 1 by the WTA, of which 14 have been year-end No. 1. The current world number one is Ashleigh Barty of Australia.
Title: List of ATP number 1 ranked singles tennis players
Content:  in the season (September). Lleyton Hewitt is both the youngest world No. 1 (20 years, 9 months) and youngest year-end No. 1, while Federer is the oldest No. 1 (36 years, 10 months). Djokovic is the oldest year-end No. 1 (34 years, 7 months). 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, 11 years, between 
Title: List of ATP number 1 ranked singles tennis players
Content: } 
Title: List of ATP number 1 ranked singles tennis players
Content:  first and last year-end No. 1 titles, 2008 and 2019. He is also the only player to be world No. 1 in three decades. Two players, Ivan Lendl and Marcelo Ríos, have reached No. 1 without previously having won a major title. 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 13 
Title: List of ATP number 1 ranked singles tennis players
Content:  Novak Djokovic has spent the most weeks as world No. 1, a total of weeks. Roger Federer has the record of 237 consecutive weeks at No. 1. Novak Djokovic also holds the record for the most year-end No. 1 rankings, achieving the feat in seven seasons. Pete Sampras held the year-end No. 1 title for a record six consecutive years. Pat Rafter spent the least time at No. 1 (one week). Novak Djokovic has the record of 16,950 ranking points, the most ATP points ever held by any player. Federer in 2004/2006, Nadal in 2010 and Djokovic in 2015 clinched year-end No. 1 the 
Title: List of WTA number 1 ranked singles tennis players
Content: } 
Title: List of ATP number 1 ranked singles tennis players
Content:  in which one player held the top spot for the entire year: Jimmy Connors in 1975, 1976, and 1978; Lendl in 1986 and 1987; Pete Sampras in 1994 and 1997; Hewitt in 2002; Federer in 2005, 2006, and 2007; and Djokovic in 2015 and 2021. In contrast to this, 1999 saw five players hold the No. 1 ranking (the most in any single year): Sampras, Carlos Moyá, Yevgeny Kafelnikov, Andre Agassi, and Rafter. John McEnroe held the No. 1 ranking on a record 14 occasions, and Sampras is the only other player to have held it on 10 or more occasions with 11 stints.
Title: List of ATP number 1 ranked singles tennis players
Content: No. 1 weeks milestones by age }}
Title: World number 1 ranked male tennis players
Content:  World number 1 ranked male tennis players is a year-by-year listing of the male tennis players who were ranked as world No. 1 by various contemporary and modern sources. The annual source rankings from which the No. 1 players are drawn are cited for each player's name, with a summary of the most important tennis events of each year also included.

Question: who is the no. 1 ranked tennis player in the world?
Answer: Rafael Nadal.