O'Sullivan began the 2008–09 season by winning the Northern Ireland Trophy, defeating Dave Harold 9–3 in the final. O'Sullivan is the only player to win back-to-back ranking events in the last four years. He then reached the final of the Shanghai Masters, having defeated Stephen Maguire in the semi–finals with two of the top breaks of 141 and 145. However, in the final, he was defeated 8–10 by qualifier Ricky Walden. In the Premier League, he secured a 7–2 win over Mark Selby, which meant that he had won the event eight times in total, and five times consecutively. However, O'Sullivan failed to defend his UK Championship title, losing to Joe Perry 5–9 in the second round. O'Sullivan had conceded the twelfth game of the match to go 5–7 down, although Perry held a lead of only 23 points to zero. Commenting afterwards, O'Sullivan said "It might have looked like I lost my head or whatever, but I'm sure I'll bounce back." For this he was later fined £300, and was ordered to pay £1,000 in costs.