This is, as Stephen Hendry alludes, the final frame before the mid-session interval.

And Ronnie O'Sullivan is at the table scoring, as he has been for most of the previous three.

Stephen Hendry
Seven-time world champion on BBC Two

If you're Ali, you've got to try to tell yourself that if you win this frame and get to the interval with Ronnie still needing two [to win], you're still in this match.

Ronnie O'Sullivan in miss shocker, as an attempted long red to the top left vibrates between the jaws of the pocket and comes away.

But Carter cannot capitalise in the early stages of frame 13.

Ronnie O'Sullivan versus Ali Carter is one of modern snooker's longest running and most twisting rivalries.

O'Sullivan had beaten Carter in world finals in 2008 and 2012 and the Masters final in 2024, although Carter did gain a win over 'The Rocket' in a bad-tempered last-16 tie at the Crucible in 2018 which included a shoulder-barge between the pair and words exchanged tableside.

More recently played out a fiercely contested Masters final in 2024, with O'Sullivan victorious.

After that encounter, O'Sullivan called Carter "not a nice person" and "a nightmare" to play against after being criticised by his opponent.

So far this match has been played out in sporting spirits - and given O'Sullivan's dominance today, we might not have any time for more drama.

This is looking very ominous for Ali Carter.

And potentially ominous for the rest of the field at the World Championship.

Three frames in a row for Ronnie O'Sullivan.

Image source, Getty Images

John Virgo
1979 UK Championship winner on BBC Two

Ali Carter had two great chances, missed two blacks off the spot, and now it looks for all money that it's going to cost him this frame.

There are still a few shots Ronnie is overhitting, a few positional plays that you feel he could do better if on his finest form.

But he's still playing magnificently here, overtaking Carter's score and looking well set to finish up.

Ah, after getting to 28, Carter leaves the cue ball too close to the cushion and he is unable to pot the black into the bottom left.

Big chance for O'Sullivan now.

Stephen Hendry
Seven-time world champion on BBC Two

If the last time he was at the table was a half-chance, this is a real chance for Ali Carter to win the frame. He has to take it, you feel.

Now, can Carter take THIS opportunity?

He has opened up the pack and is well placed on the pink and blue. A real chance to build a break and reduce the frame deficit to two.

Luca Brecel takes the second frame to level things up against Ryan Day.

Brecel just needs the brown to leave Day needing a snooker but he lands awkwardly - so the Belgian slams a double into the middle pocket and that's enough to get his first frame on the board.

Ali Carter has a 42% pot success rate so far today. He would be annoyed at that if he was having a knockabout down the pub, let alone at the Crucible.

Not a couple of shots either man will want to remember here.

After potting a difficult long red, Carter fails to follow up with the black off the spot, cueing from tight on the cushion.

But then O'Sullivan misses a red into the right middle.

Carter gets to 14 before he is forced to play safe.

It's a better safety though, and it forces an error from O'Sullivan who kisses the yellow to give his opponent a chance...

But the long pot from Carter is missed!

Image source, Getty Images

Polite applause as Ali Carter finally gets on the scoreboard for the first time in this session.

You would think Carter needs to get a good score on this visit to at least put a marker down today.

Mark Allen
Former Masters and UK champion on BBC Two

Frames go fast against Ronnie. It was 15 seconds per shot in that last break.

In the blink of an eye, Ali was one behind and now he's three behind. He's got everything to do.

Until the opening session of this match, Ronnie O'Sullivan had not played competitively since January when he snapped his cue and threw it in the bin following four losses in five matches at the Championship League event.

He subsequently withdrew from a number of tournaments, including the Masters, the Welsh Open and the Grand Prix, saying he "needed to prioritise his health and wellbeing".

Before the tournament, O'Sullivan told BBC Sport "to come here is an achievement in itself for me" as he documented his technical struggles.

O'Sullivan only confirmed his appearance at the tournament late last week, marking a 33rd successive year at the Crucible after he made his debut in 1993, aged 17.

Some vintage Rocket on display, with his 1,284th career century. Thanks John Virgo for the stat.

It's a break of 117, the best of the match, to open up some real daylight to Carter.

A slight overshoot after a red is no worry for O'Sullivan, who calmly pots the black to Crucible applause.

Carter will stay in his seat once this break is done, pondering a three-frame deficit.