Perry opened 2008–09 with three last-sixteen runs, leaving him inside the top eight of the provisional rankings. However he went one better in the 2008 UK Championship beating Ronnie O'Sullivan 9–5 having trailed by 3–5, in one of the best victories of his career. However, he lost 7–9 to Marco Fu in the quarter-finals. In the new year, he suffered a narrow 5–6 loss to O'Sullivan in the Masters; the rest of the season was unspectacular as he failed to win a match in a ranking event. He was unable to repeat his 2008 run in the World Championship, losing 6–10 to an in-form Jamie Cope in the first round. This meant that he finished the season ranked at number 12. In 2009–10 he only reached one quarter-final and consequently slid to 19th in the rankings. In the World Championship he beat Michael Holt in the first round 10–4, and trailed Ali Carter 6–10 before winning five frames in a row to lead 11–10 but lost 11–13.