After the US Open, del Potro played in the Davis Cup semifinal against Serbia, winning both of his rubbers against Janko Tipsarević and world No. 1 Novak Djokovic. This helped Argentina to a 3–2 victory over Serbia in the semifinals, booking their place in the final. He then played in the Stockholm Open, losing in the second round to James Blake. He then reached the final in Vienna, losing for the first time to Jo-Wilfried Tsonga. Despite having won the first set, he eventually lost the final. Del Potro then reached the semifinals of the Valencia Open 500, losing to eventual champion Marcel Granollers. He then withdrew from the Paris Masters due to a shoulder injury, wiping out his chances of qualifying for the Year-End Championships.