Big names crash out on day of shocks at World Snooker Championship

Allen had been viewed as one of the top contenders for the title and looked set to streak through to round two after opening the match with successive breaks of 136 and 105.

But Clarke responded with a 136 of his own and the 25-year-old remained composed throughout, winning four straight frames from 6-4 down to seize control and go on to claim by far the best win of his career.

Clarke's feat was matched by Saengkham, who exploited a series of uncharacteristic errors from Murphy to become only the third Thai player to win a match in Crucible history.

Afterwards Murphy stressed his performance had not been affected by the recent sudden death of his former manager and mentor Brandon Parker, whose funeral he attended in the Algarve last month.

Murphy told BBC Sport: "I was very much below par across the whole match – probably the worst two days of my snooker years came together at the worst possible time.

"My form has been good this season with two titles and other finals, so this was a shock to me.

"And I can say that the build-up to the tournament had no impact. I came here wanting to honour Brandon Parker's memory.

"You dream of winning the title and dedicating it to him and things like that. But I would never dishonour him by saying that has caused me a problem."

Saengkham, who admitted he barely slept on Monday night, showed no sign of nerves as he produced breaks of 53 and 63 to extend his advantage to five frames.

A rare missed red enabled Murphy to temporarily reduce the deficit, but further breaks of 60 and 74 either side of the mid-session interval saw Saengkham ease home.

Saengkham estimated up to one million people will have watched the match in a country whose appetite for snooker was largely cultivated by the exploits of former world number three and two-time Crucible semi-finalist James Wattana.

He said: "James taught me everything – how to come here and speak the language. He taught me how to get through because for an Asian player to come to the UK is difficult.

"I felt a lot of pressure but I just tried to concentrate on the table and not think about all those people watching me.

"For the last three or four days I have turned my phone off and not done anything on the internet. If I turn my phone back on it will be too much pressure with all the messages."

Mark Selby avoided a similar fate to Murphy but was far from his best as he laboured to a 10-6 win over qualifier Jordan Brown.

Resuming 5-4 in front after Monday's opening session, the three-time champion extended his advantage to three frames with consecutive half-centuries.

A series of uncharacteristic errors allowed the Antrim 32-year-old to drag back to within one frame at 7-6 before Selby managed to battle his way over the line.

Selby said: "Obviously with no crowd you don't know how you're going to feel and at times my focus was in and out because of the situation.

"I definitely prefer playing in front of a full crowd. Sometimes if you're struggling you can easily be out there and start losing a few frames and think the world's against you because there's no-one cheering you on.

"But when things are going well it doesn't matter whether there's a full crowd or not. If you're in the zone, you don't notice the crowd anyway."

Qualifier Martin Gould fired four centuries and three more breaks over 50 on his way to establishing a 7-2 overnight lead against ninth seed Stephen Maguire.