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 rookie Oliver Lines came from 0–4 behind to defeat him 6–4. In the invitational Champion of Champions tournament, he reached the quarter-finals, but lost 1–6 against Judd Trump. He suffered another early exit at the UK Championship when he lost 4–6 to David Morris in the last 64. Playing Shaun Murphy in the first round of the Masters, Selby fell 1–5 behind before recovering to 5–5, but lost the match 5–6 on the deciding frame. It was the first time that Selby lost in a deciding frame at the Masters, having won the previous 11 deciding frames. At the German