Mark Selby in the last 64. In the first round of the Masters, Selby played against Mark Willams in a repeat of the 2017 edition. However, it was Williams who prevailed in their encounter 6–5. It was also the second time that Selby lost in a deciding frame at the tournament. Selby retained his China Open title, defeating Barry Hawkins 11–3 in the final. It was the 3rd China Open title he won in 4 years. Selby's two-year reign as World Champion came to an end at the first round of the 2018 World Snooker Championship. Facing Joe Perry, Selby trailed 2–7
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