Defending champion in the singles was Roger Federer , but this year he was eliminated in the quarter-finals. This year's final was played by Novak Đoković and Andy Murray . Đoković gave up in the second set and lost a match for the second time this season. For Murray it was the second season and the 18th ATP title of his career. He won the Cincinnati tournament for the second time after 2008. In doubles, Bob and Mike Bryan defended their title, but lost in the semifinals against Mahesh Bhupathi and Leander Paes , who then defeated Michaël Llodra and Nenad Zimonjić in the final. For Bhupathi and Paes it was the third title of the year and the 26th joint title overall, while it was the first defeat for Llodra and Zimonjić after two final wins in a row.
The field of participants in the single competition consisted of 56 players, that of the double 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 $ 2,592,000; total financial liabilities were $ 3,200,000.
The qualification took place from August 13-14, 2011. Seven qualifying places were played, which entitle them to participate in the main draw of the tournament.
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. The prize money for the double competition is valid per team.