Most tennis fans are seen scratching their heads when they learn that their favorite player has dropped down the rankings, even though they did not lose any tournaments in the past few weeks. For those who do not try to understand how the ATP ranks tennis players, it can be downright confusing to see players move up and down the rankings, irrespective of the tournaments they play, or for that matter, don't play. Well, if you thought that professional tennis players were ranked randomly, think again. There is a confusing system in place that decides which ranking a player gets, and in the following paragraphs, we try to explain that in a very simple manner. How are Tennis Players Ranked by the APT? As mentioned, the ATP ranking system is a bit confusing to explain properly. Of course, a player gets points for the tournaments he plays in, and the points for those tournaments keep increasing as the player progresses in the tournament. For example, consider a tournament which has four rounds, a quarter final, a semi-final, and then the final. Players will receive more points the further they advance in the tournament. So, a first round loser might get 5 points, while a semi-final loser might get 200 points. The winner, of course, gets the highest number of points. The points are ATP Ranking Points, and are used to determine the rankings for the year. Unfortunately, it's not that simple though. There are two or three more twists to this ranking system that can boggle the mind. The first twist is that there are different tournaments that offer different points. For example, Grand Slams offer 2000 ATP Ranking points to the winner, while ATP World Tour 250 Events offer just 250 points to the winner. Of course, there are just the four Grand Slams in the year, while there are about 40 ATP World Tour 250 Events in the year, so it works out. So, there are different tournaments across the year―Grand Slams, ATP Tour 1000 Events, ATP Tour 500 Events, ATP Tour 250 Events, and Challenger and Futures Series, that all give different points to the players, again, depending on how far they advance in the tournament. The second twist that makes this ranking more difficult to understand is the concept of the 'rolling point system', along with the amount of titles considered to ranking points. The rolling concept is something where the points that a player earns from tournaments are kept till the next time those tournaments occur, i.e. one year, When he competes in that tournament again, his performance in that tournament will determine his points. Confusing? Let me explain with an example. Let's say a player wins the 2009 US Open title. For that he gets 2000 ranking points. These 2000 ranking points stay with him till the 2010 US Open, where his performance in the 2010 US Open will determine the ranking points he gets. If he wins the title again, then he 'retains' or 'defends' his 2000 points. However, if he loses in the semi-final, he gets just 1000 points, thus effectively losing 1000 points of his previous year's 2000 points. If he cannot play in the tournament, he is unable to defend his points and loses them all. This system is calculated for all tournaments, based on a 52-week ATP calendar. The third twist is the number of tournaments that are taken into account for the ranking. The ATP has fixed a number of tournaments from which the ranking points are taken and counted towards the year-end ranking. The four major grand slams, 8 ATP World Tour Masters 1000, and the year-ending Barclay's ATP World Tour Finals are the mandatory events that count towards the players ranking. In addition to these 12(+1) [you have to qualify for the Barclay's ATP World Tour Finals] tournaments, a player's 4 best results from the ATP World Tour 500 series, and 2 best results from the ATP World Tour 250 series [including Challenger and Future Series] are included in the ranking. So, there are a total of 18(+1) tournaments that the ATP looks at while determining a players ranking. Based on all these factors, the ATP ranking system is determined, and players are ranked for the year. With the current 52-week rolling policy in place, it has become more difficult for players to earn points. They have to be consistently winning tournaments to be highly ranked, as the ranking does not have any start and end dates.