Mark Selby Open, losing 1–4. Selby won his first ranking title of the 2017/18 season by retaining the International Championship after surviving a fightback from Mark Allen, who trailed 3–8 and 7–9 in the final but the Englishman prevailed 10–7. As 2017 World Snooker Champion, Selby automatically qualified for the 2017 Champion of Champions. However, he lost in the quarter-finals to Luca Brecel by a scoreline of 4–6. At the 2017 Shanghai Masters, Selby crashed out to 2011 finalist Mark Williams in the quarter-finals 3–5. Selby's reign as the UK champion came to an end with a 3–6 defeat to Scott Donaldson
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