Mark Selby to begin World Championship defence against Ireland's Fergal O'Brien at Crucible

Mark Selby will open up his title defence against Fergal O'Brien

Mark Selby will launch his Betfred World Championship title defence against Ireland's Fergal O'Brien on Saturday.

After winning the world title in 2014 and 2016, and sitting at the top of the world rankings for the last two years, Selby is regarded as the man to beat at the Crucible this year.

The 33-year-old from Leicester also won the China Open at the start of April after coming from behind to defeat Mark Williams 10-8 in a thrilling final.

Fergal O'Brien won the longest frame in professional snooker history

He faces 45-year-old O'Brien, who was part of a world record on Wednesday night when he won the longest frame in the history of professional snooker, taking two hours, three minutes and 41 seconds to win a decider against David Gilbert to book his place in the main draw.

Their match will begin at 10am on Saturday, with the champion playing first in accordance with tradition as the tournament gets under way.

Ronnie O'Sullivan last landed the world title when achieving back-to-back successes in 2012 and 2013, and the five-time winner will face Wallsend cueman Gary Wilson in his opener. Wilson is one of five debutants in the draw.

Chinese 17-year-old Yan Bingtao is expected to have a big future in the sport and will tackle 2005 world champion Shaun Murphy first up.

Selby has also lifted the UK Championship trophy this season back in December

Zhou Yuelong, 19, makes his first appearance in an all-Chinese clash with last year's runner-up Ding Junhui.

Of the other newcomers, Leeds cueman David Grace starts against Kyren Wilson, who reached the quarter-finals last year, and Thai player Noppon Saengkham faces a tall order against Australia's 2010 world champion Neil Robertson.

Four-time champion John Higgins plays the dangerous Martin Gould, while the strongly fancied Judd Trump, the 2011 runner-up, has veteran Rory McLeod in the first round.

A clash of former champions sees Stuart Bingham play Peter Ebdon, while 2006 Crucible king Graeme Dott is rewarded for qualifying this time with an opener against two-time former runner-up Ali Carter.

An all-Scottish clash sees Anthony McGill set a tough task against qualifier - and former semi-finalist - Stephen Maguire.