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 defeat. Despite this he finished the season as the world number one for the fourth year in a row. Selby's first semi-final of the season came at the International Championship courtesy of knocking out Neil Robertson 6–4, but he lost 9–4 to John Higgins. Selby did not drop a frame in reaching the third round of the UK Championship and saw off Jamie Jones 6–5, admitting later that his opponent had deserved to win the match. He then eliminated Dechawat Poomjaeng and Matthew Selt both 6–1, before being whitewashed 6–0 by Robertson in the semi-finals. Selby lost in the quarter-finals