Zhao Xintong is seven frames ahead so he doesn't really need the benefit of the run of the balls at the moment - but he gets it when he misses a green and it travels around the angles to drop into the middle pocket.

He won't win the frame in one visit though - his break ends on 31 - but he returns soon after to pot a red to the middle.

The players are back out for four more frames to complete this third session.

If Zhao Xintong wins all four, he will be world champion.

And the Chinese sensation starts with a powerful long red into the right corner.

This is the seventh meeting between Mark Williams and Zhao Xintong.

Williams has a 4-2 lead, although Zhao has won the two most recent matches between the pair.

Barring a sensational comeback, the 28-year-old from China will be making it three wins in a row against the three-time world champion from Wales.

Steve Sutcliffe
BBC Sport at the Crucible Theatre, Sheffield

Zhao Xintong is already guaranteed £200,000 just for reaching the final.

And while he is currently playing under amateur status, that matters not when it comes to collecting prize money here.

He is returning to the main professional tour next season and has his eyes set on the £500,000 top prize and a place in history as the first world champion from China.

If he were to achieve that, he would move to 11th in the world rankings. If he is not holding the trophy today, he will find himself ranked 29th in the world.

Sam: Is there anything Zhao can’t do, beating Ronnie with a session to spare is rare enough but winning the world championship with a session to spare is insane, unless Mark wins a frame after the interval.

David: Looks like it'll be the Great Escape tonight, then?

John Parrott
1991 world champion on BBC Two

Reflecting on losing the 1989 world final heavily to Steve Davis:

I was done at 12-3. I had nothing left. I was lucky to get three. There's nothing you can do, no matter what you try, your arm doesn't feel your own and you feel deflated.

It gets frustrating because you know you're so much better than what you're doing.

Ken Doherty
1997 world champion on BBC Two

Zhao's not flinching and when the winning line comes, I think he'll run right through it.

At the moment, things are rubbing against Mark Williams. He looks like he's deflated a bit, he needs something to inspire him.

For the first time in this World Championship final, Zhao Xintong has a seven-frame lead.

He has won three of the four frames this afternoon.

Zhao Xintong leaves a red over the corner but Mark Williams has to swerve around it to pot it. He does - but goes in-off!

The last red is behind the black and Zhao can't see it fully, so Zhao takes the green as his free ball to level the score.

And when Zhao pots that last red along the top cushion, that makes him a strong favourite for the frame.

Zhao Xintong's first reply ends on 12 following a poor positional shot off the blue, but he's back to drop in another long red and will hope to add another frame to his tally.

Mark Williams tries to split the remaining reds off the brown but doesn't land on anything, so has to play safe.

He's 45 points in front but that advantage can disappear very quickly when Zhao Xintong is in the mood.

Mark Williams starts frame 21, the last frame before the mid-session interval, with a superb long red.

The story of his final has been some excellent single pots but not being able to follow them up with too many frame-winning contributions.

He's made four half-century breaks in this final but no centuries, with a highest break of 86.

Ken Doherty
1997 world champion on BBC Two

It's actually quite scary, some of the balls Zhao is potting. Does he realise he's in a world final?

He's doing it so effortlessly, he looks so relaxed. He plays with a smile on his face - he's absolutely loving it.

Steve Davis
Six-time world champion on BBC Two

Unless something dramatic happens, we are looking at the world champion here.

It's an interesting talking point regarding how fresh both players may be feeling in this final...

Zhao Xintong wrapped up his semi-final on Friday evening so had a day off on Saturday, while Mark Williams played two sessions against world number one Judd Trump.

But Zhao - 22 years younger than Williams - has played four extra matches in qualifying to reach this stage. His tournament started on 7 April, so could that be a factor in the final stretch?

Ioan Morris: I've long felt that the lack of a rest day between semi-finals and final is ridiculous, especially for the player in the Saturday evening session. It simply isn't a fair way to schedule a tournament.

John Parrott
1991 world champion on BBC Two

The balls were horrible. [Amazing] to make 58 from where he did. It was like a computer game. A fabulous break.

"Stop it," shouts John Virgo as Zhao Xintong floats in another wonderful long red, which has been one of the trademarks of his tournament.

He's 51 in front with 43 remaining and on the brink of a 13-7 lead.

When Mark Williams fouls by potting the black, the frame is conceded.

Steve Davis
Six-time world champion on BBC Two

Somewhere down the line, you can be excused for being a bit panicked as you get closer to winning. But Zhao has looked as cool as a cucumber.

What a hurtful frame he's putting together here for Mark Williams.

Image source, PA Media

Zhao Xintong began this season suspended from snooker after a match-fixing scandal but has been tipped by Ronnie O'Sullivan to be the sport's new "megastar" if he becomes the first Chinese player to win the World Championship.

The 28-year-old, who lives just a 10-minute walk from the Crucible venue in Sheffield, is closing in on joining Terry Griffiths and Shaun Murphy as the only qualifiers to land snooker's biggest prize since the tournament's 1977 move to South Yorkshire.

• Read more about Zhao's return to snooker and his run to the world final