Mark Selby with a shock 3–5 defeat to Andrew Pagett in the qualifying rounds of the 2013 Wuxi Classic. The tournament was the first to use a new format that required top-16 players to compete in qualifiers. In minor-ranking tournaments, Selby was runner-up in the Yixing Open, where he lost 1–4 to Joe Perry, and the Rotterdam Open, where he lost 3–4 to Mark Williams. He won the Antwerp Open, defeating Ronnie O'Sullivan 4–3 in the final. In December, in the seventh frame of his UK Championship semi-final against Ricky Walden, Selby compiled snooker's 100th officially recognised maximum break in professional competition.
Mark Selby 3–5 first round defeat to Jamie Burnett in the Australian Goldfields Open. Selby lost his world number one spot to Judd Trump after the latter's victory in the inaugural International Championship in China. However, just five weeks later, Selby won his third ranking title and largest of his career, the UK Championship, to regain the top spot. He defeated Michael White 6–3, Ryan Day 6–4 from 3–0 down, and Neil Robertson 6–4 from 4–0 down to reach the semi-finals, where he beat Mark Davis 9–4 to progress to the final. Already assured of overtaking Trump regardless of the result, Selby