Defending champion Mark Selby has been sensationally knocked out of the World Snooker Championship by Joe Perry in the first round, losing 10-4.

Selby had not lost a match at the Crucible Theatre since 2015, winning each of the last two instalments of the tournament to move on to three world titles.

However, the 34-year-old has struggled for form this season and - despite coming into the World Championship on the back of a win at the China Open - had suffered early exits at the UK Championship and the Masters.

Qualifier Perry opened up a 4-0 lead over the world number one and, while Selby managed to pull back to 4-2 after the interval in the opening session, the 43-year-old quickly re-established his cushion to begin the evening session 7-2 in front.

Selby could only claw back two frames on the first night of the tournament, as Perry wrapped up a memorable victory with a 90 break.

The result marks a first opening-round exit for Selby since 2012, when a neck injury hampered him in a defeat to Barry Hawkins.

Perry, who has not been beyond the second round since reaching the 2008 semi-finals, will face the winner of the match between Masters champion Mark Allen and Crucible debutant Liam Highfield.

Second seed Ronnie O'Sullivan also endured a difficult day on Saturday - he trails Stephen Maguire 6-3 ahead of their second session on Sunday.