World Amateur Golf Ranking
The World Amateur Golf Ranking for men was introduced by The R&A, the governing body of the sport of golf outside the United States and Mexico, on 23 January 2007. It is based on the results of over 2,600 amateur tournaments per year (and amateurs participating in certain professional events) and is updated each Wednesday. Rankings are based on the players' average performances in counting events over a rolling period. This period was 52 weeks initially but was gradually expanded during 2016 to 104 weeks, similar to those of the Official World Golf Ranking.
Like the Official World Golf Ranking for male professional golfers, the amateur ranking was initiated by The R&A to provide a more reliable means of selecting an appropriate field for one of its tournaments. The professional ranking was initially used to help set the field for The Open Championship and the amateur ranking plays a role in selecting the field for The Amateur Championship, which was previously selected mainly on the basis of national handicap systems. Other tournament organisers will be able to use the rankings to select players if they so wish.
In February 2011, the United States Golf Association (USGA) endorsed the rankings and announced it would use them for an exemption category in all their men's amateur championships, including the U.S. Amateur, beginning in 2011.
Only three male and one female players have ever held the No. 1-ranking as both an amateur and a professional. The first to do so was Rory McIlroy, who was 17 years, 9 months and 2 days when he became the No. 1 amateur and 22 years and 10 months when he first became the world No. 1 professional. Jordan Spieth was the second to accomplish this feat, he was 18 years, 10 months and 24 days when he topped the amateur rankings and 22 years and 20 days when he reached No. 1 in the Official World Golf Ranking. Jon Rahm, who was ranked no. 1 for 60 weeks, became professional world no. 1 in July 2020. Lydia Ko is the only player to accomplish this feat in the female ranking. She was only 14 years and 3 days and held the ranking for a record 130 consecutive weeks, and she was a mere 17 years, 9 months and 9 days when she first reached the pinnacle of the Women's World Golf Rankings.