Stephen Hendry was tonight on the receiving end of the sort of destructive performance he regularly inflicted on opponents in his pomp as Mark Selby made him suffer at the Crucible.

In the opening session of their second-round clash at the World Championship, Selby had breaks of 125, 108, 98 and 129 as he built up a 7-1 advantage.

Seven times a winner of the world title in the 1990s, Hendry looks to be heading out of what could be his final Crucible visit as a player, having admitted retirement is an option for him this summer.

It could be a painful exit, particularly if Selby beats him with a session to spare.

They return tomorrow to resume their battle and are due to finish on Monday afternoon, however with Selby requiring just six more frames to reach the quarter-finals it could be over early.

There was a reminder of Hendry's brilliance when the 42-year-old fired a break of 114 in the second frame, but it was fleeting.

Mark Allen claimed another plucky final-frame thriller and went close to 147 glory as he booked a place in the quarter-finals.

It looked like Allen was crumbling as he let a 12-9 lead over Barry Hawkins slip away, having earlier fought back superbly from 7-3 behind to go in front.

But he was gifted an immediate chance in the decider when Hawkins ran in to the blue off his break, and Allen plundered 12 reds and 12 blacks.

But off the last of those blacks he suffered a kick, and rattled a long red around the jaws of the green pocket, halting the break on 96.

Allen said: ‘I don't do things the easy way.

‘I was just hoping to get a chance in the last frame because he'd played so well.

‘I've never been so happy to see someone hit a blue off the break and give me a chance, because in a deciding frame that's all you're wanting.

‘Luckily I knocked the red in and made a good break.’

Allen plays fellow left-hander Mark Williams next and is relishing his clash with the world champion of 2000 and 2003.

‘I'm looking forward to it,’ Allen said.

‘I haven't played Mark in a long time. Obviously he's provisionally world number one now which is a major achievement considering he dropped to 42nd in the rankings at one point.’

And when asked if this could be his year at the World Championship, Allen said: ‘There's no reason why not.

‘I've only got seven people left to beat. And obviously I'll only have to beat three of them on the way. Anyone who's in the quarter-finals can win. But Williams is going to be a tough man to beat.’

Hawkins said: ‘It was a horrible way to go out.

‘I gave Mark a chance and he made a great break.’

Ronnie O'Sullivan's second-round match against Shaun Murphy had been billed a grudge contest, but when O'Sullivan opened up a 6-2 lead this afternoon it was threatening to become a no-contest.

There was not a great deal to enjoy about the opening four frames, as the pair began, after a handshake, as though the enormity of the occasion was smothering them.

It hardly helped that the air-conditioning system in the arena had broken down, making for a humid atmosphere.

But gradually O'Sullivan began to impress, and he had breaks of 76, 75 and 86 in the final three frames of the session to pull clear.

Murphy branded O'Sullivan's behaviour as ‘pathetic’, ‘disrespectful’ and ‘unprofessional’ last September, when he had to be coaxed by referee Jan Verhaas to pot the final black to complete a 147 at the World Open in Glasgow.

The pair are very different characters, with Murphy never short of an opinion. One which he holds is that there is a distortion in the ratio of the attention O'Sullivan commands and what he brings to the sport compared with other players.

Clearly, though, O'Sullivan could be grabbing many more plaudits over the next week and a half, as he looks in the mood and in the shape to land what would be his fourth world title.

O'Sullivan has praised the sports psychiatrist he turned to after withdrawing his threat to pull out of the World Championship.

He has only recently begun work with Dr Steve Peters, who has previously operated to successful effect with Britain's Olympic cycling team, but the initial results seem impressive.

Heading into the match, 35-year-old O'Sullivan wrote on Twitter: ‘Change of heart has been helped by Dr Steve Peters. Amazing man. It's early days but I'm enjoying the game much more.

‘The key is to enjoy. As long as I enjoy playing I will continue to play. If not then I can't carry on . It was killing me :(‘

A player hoping to be crowned for a second time at the Crucible is Scotland's Graeme Dott, always a threat in Sheffield and a quarter-finalist again.

Dott, 32, set up a showdown with snooker's new golden boy Judd Trump by overcoming Ali Carter 13-11.

Their match ran to a theme of Carter setting up frame-winning positions and allowing Dott to steal in at the end to deny him.

Devastated Carter said he was ‘absolutely robbed’ of frames he should have won, and Dott acknowledged: ‘I stole so many.’

The 2006 champion is wary of 21-year-old Trump, who won the China Open at the start of the month and then knocked out defending champion Neil Robertson on the opening day of the World Championship.

Today saw Trump finish off a 13-6 mauling of Martin Gould, and Dott knows he poses a threat, particularly since he has never known any agony at the Crucible.

‘You can tell he's just free-rolling here,’ Dott said. ‘He's got no battle scars, that's why he's enjoying it.

‘I can remember being here and enjoying it, but give him another five or six years.’

Trump continues to believe he can carry off the title.

‘I'm definitely super-confident. I feel like I've got the game to go out and win it,’ Trump said.

‘I'm on such a high, I've got used to winning whereas I was used to losing before.’