Qualification
Spots were awarded to the top seven players highest ranked single players in the world ranking. And The top seven doubles teams in the 2009 ATP Doubles Race. With one spot reserved for Grand Slam champions who finish outside of the top 8, but within the Top 20 players or teams. As this did not happen, the final spot went to the next player or team in the top 8. Two additional players and teams were also in London as alternates in case of withdrawals.
Read more about this topic: 2009 ATP World Tour Finals