The biggest break of the evening, 68, sees Zhao Xintong go 10-4 ahead.

Looking ominous now for Chris Wakelin. He really needs both of tonight's remaining frames.

Mysteron_Voice: John Higgins keeps getting these chances, but you just don't fancy him to take any of them.

John Virgo
1979 UK Championship winner on BBC Two

The final session is tomorrow and John Higgins will want to keep himself close. Tomorrow is another day. He will not let his head drop here. At 37-28 in Higgins' favour this frame is still very much in the balance.

We asked you to hit the thumbs on Zhao Xintong's return after his ban, and it's provided a mixed response.

Rob Walker
Commentator on BBC iPlayer

If Zhao does make the semi-finals, he has to cut out the unforced errors to stand any chance.

Zhao Xintong is now 9-4 ahead despite numerous mistakes, among some good potting. Remember, it's most likely that Ronnie O'Sullivan awaits in the last four.

A break of 20 apiece for Mark Williams and John Higgins but the table is a bit of a jungle with the blue, pink and black all nestled into a cluster of reds. Safety-first approach from both players again.

Simon Gray: Had a fantastic five days in Sheffield attending seven sessions of the World Snooker Championship It’s become my favourite annual trip to a sporting event and always sad to leave. It’s a great atmosphere around the place and you can’t fail to get chatting to like minded, nice people

Image source, Getty Images

A bit of scrappy frame but Mark Williams' potting sees him close it out and get himself in front.

John Higgins dashes off at the end of the frame. He's struggled this evening and needs a pick-me-up from somewhere.

John Higgins has a furrowed brow. Once again he cannot quite get himself going and Mark Williams is able to slide up to the table and start his precision potting. Williams is 52-18 up with both players attempting to outfox each other with the final red.

Bob McFeil, Esq: I’ve never been so captivated by a safety-dominant match but John Virgo and Stephen Hendry on commentary are simply marvellous. Mellifluous, erudite and witty accompaniment to the masterclass on display. Delightful evening on the sofa.

John Virgo
1979 UK Championship winner on BBC Four

Mark Williams is in the ascendency but John Higgins should not forget the match is all square. Williams seems to be biding his time waiting for Higgins to make a mistake.

Where do you stand on Zhao Xintong's return?

A talented player who served his time after getting mixed up in the wrong company? Thumbs up

Or someone who should still be suspended, never mind competing in the world championship? Thumbs down

Steve Sutcliffe
BBC Sport at the Crucible Theatre, Sheffield

Image source, Getty Images

Zhao Xintong could become the first ever amateur to win the World Snooker Championship at the Crucible if he carries on at this rate.

But of course there is a slight anomaly in that, given he won the UK Championship in 2021, has already competed in Sheffield before but was then one of 10 players banned in 2023 following an investigation into match-fixing.

He did not directly throw a match, but accepted charges of being a party to another player fixing two matches, and betting on matches himself.

He returned earlier this term to the Q Tour and is technically still prohibited from playing in mainland China under the suspension given to him by the Chinese Billiards and Snooker Association.

However, that is set to end in July so it will not cause him any problems when he returns to the professional tour next season.

The CBSA had also signalled to authorities in the UK that they had no issues with him competing at both the UK Championship and World Championship.

A dreaded double kiss scuppers Chris Wakelin and Zhao Xintong restores a four-frame cushion going into the mid-session interval.

He should really be further ahead.

John Higgins just cannot find any rhythm at the moment. A small break to start the 13th frame but he is unable to build it into anything significant and resorts to safety.

I think we might have a winner already...

Image source, PA Media

Ken Doherty
1997 world champion on BBC Four

It is a great session for Mark Williams so far. A couple of great long pots and we know he is one of the greatest long potters we've ever seen. He looks the stronger of the two players at the moment and probably didn't want the interval to come to stop that momentum.

Image source, Getty Images

Seven-time winner Ronnie O'Sullivan opened up a commanding 6-2 lead over Si Jiahui in the first session of their World Championship quarter-final.

O'Sullivan, who is bidding for a record eighth title in the modern era, took a scrappy opener before Si responded with a wonderful century break.

However, the 22-year-old from China uncharacteristically missed a series of pots to allow 'The Rocket' to pull clear at 4-1 with three half-centuries.

While Si responded with a 60 of his own to briefly reduce his arrears, another miss, on a black on its spot, proved costly as O'Sullivan pinched the seventh frame.

The Englishman concluded the session with a stylish 121 break to underline his superiority.

Read the full report...

Stephen Hendry
Seven-time world champion on BBC Four

This is exactly how we expected this match to go. It's been hard fought and now there's nothing to choose between the two players.

John Virgo
1979 UK Championship winner on BBC Four

It looks like Mark Williams who appears to be scoring better at the moment. John Higgins will come out after the mid-session interval and have to up his game.