Defending champion in the singles was Andy Murray , who was eliminated in the semifinals against the eventual winner Roger Federer that year . In the final, Federer defeated the Serb Novak Đoković in two sets with 6: 1 and 7: 5. After 2005 and 2007, it was Federer's third success in Cincinnati and his fourth title this year. The brothers Bob and Mike Bryan competed in doubles to defend their title. They made it into the final again this year, but lost to the duo Daniel Nestor and Nenad Zimonjić , who won in three sets with 3: 6, 7: 6 2 , [15:13].
The field of participants in the single competition consisted of 56 players, that of the doubles competition consisted of 24 pairs. The eight top seeded players in singles or pairings in doubles each got a bye into the second round. The total prize money was $ 2,430,000; total financial liabilities were $ 3,000,000.
The qualification took place from August 13-14, 2009. Seven qualifying places were played, which entitle them to participate in the main draw of the tournament. There was also a lucky loser.
The following prize money and world ranking points were paid out or credited for reaching the respective round. Players who moved into the main draw via qualification received the specified qualification points in addition to those for reaching the respective round. Otherwise the amounts are not to be understood as cumulative. Prize money for the double competition applies per team.