ANTHONY McGill admits he is still coming to terms with the biggest win of his career after causing one of the biggest shocks in World Snooker Championship history to beat defending champion Mark Selby on Friday.

The Glaswegian potter was ruthlessly efficient in building a 10-6 lead in the morning session before staying remarkably composed to clinch a 13-9triumph.

Breaks of 68 and 87 moved McGill within one frame of victory and although Selby tried to stage one of his trademark comebacks, the 24-year-old held his nerve with an 82 to get over the line.

The Crucible debutant, a 150/1 outsider for the title before the tournament, was calmness personified and claims the fact his scalp was Selby made it all the more special.

"I'm just ecstatic - I'm bouncing to be honest with you," said McGill. "I'm over the moon to beat the world champion.

"Even when I was ahead I said to myself, this guy is not world champion for no reason. He's renowned for his comebacks, so I can't let him back in it. I thought if he got a couple of frames then I'm in trouble.

"I was just really determined to play well and win. I wanted to make my chances count. Not many guys beat the world champion, let alone at the Crucible. It's the biggest win of my career, without a doubt."

McGill's reward for beating the world No.1 is a quarter-final clash with either Joe Perry or Shaun Murphy starting on Wednesday.

The world No.32 will try to become the first man since Andy Hicks in 1995 to reach the semi-finals on their World Championship debut and although he is now being tipped as a potential champion, the youngster is refusing to get ahead of himself.

"I've got two arms, two legs and a cue, so you never know what will happen next," added McGill. "I will try my best but I know I will be a massive underdog whoever I play

"I'm going to have to play exceptionally well to win but I might as well enjoy it when it is happening."

Meanwhile, John Higgins faces a tense final session in his last 16 contest with Ding Junhui after the Chinese sensation made a stirring comeback in Sheffield.

The Wishaw cueman led 5-1 early in the match, and 5-3 overnight, but Ding fought back to lead 9-7 as the pair prepare to play to a finish at 10am on Saturday.

Elsewhere, 2006 world champion Graeme Dott made a slow start to his last-16 contest against England's Stuart Bingham - trailing 9-5.