Troicki reached another final in the Thailand Open. After defeating Thomaz Bellucci, 6–3, 7–6 in the round of 16, he then defeated eighth-seeded American John Isner 7–6, 6–2, in the quarterfinals. In his semifinal match, he went on to upset the defending 2008 Bangkok champion, 2008 Australian Open finalist, and top seed Jo-Wilfried Tsonga, 1–6, 6–2, 6–3 to reach his second ATP World Tour final to face the second seeded Gilles Simon. He lost 5–7, 3–6. He then competed in the 2009 China Open, where he lost in the second round to compatriot and eventual champion Novak Djokovic 3–6, 0–6. He then competed in the Shanghai ATP Masters 1000, where he lost to eighth seed Gilles Simon, 3–6, 4–6, after defeating Juan Mónaco 6–1, 6–2, in the first round. He was then upset by Karol Beck in the first round of the St. Petersburg Open, marking his 10th first-round loss in 25 tournaments. He then defeated Benjamin Becker 6–2, 7–6, before losing to Marin Čilić in the second round in a close three setter 6–7, 7–6, 6–7, in the Swiss Indoors. He played his last tournament in the BNP Paribas Masters, losing in the second round to Radek Štěpánek 4–6, 2–6, after defeating Paul-Henri Mathieu 7–6, 3–0 ret.