The referee warns Mark Allen that there may need to be a re-rack, and for the frame to start again.

"I was always hoping the black was going to drop in, obviously.

"But that is not happening."

Steve Sutcliffe
BBC Sport at the Crucible Theatre

The last pot in the frame was 45 minutes ago. We are heading up to the hour mark and possibly the longest frame of the World Championship - an unwanted distinction.

The referee is getting tetchy with the ironic cheers from the crowd now after each safety shot.

"We don't want that, settle down" he says.

Wu Yize can see the funny side at least.

Stephen Hendry
Seven-time world champion on BBC Two

The referee has got to call this, I'm afraid.

I think he should've called it a while ago.

John Parrott
1991 world champion on BBC Two

I've never seen a frame like it in all my years.

I've never seen it this bad.

Still locked in a stalemate with the reds grouped round the black and tit-for-tat safety shots.

Think our best hope is Ray Winstone as 'Carlin' popping through the doors, scooping some of those reds into a sock then telling everyone to "carry on".

BBC Two

This match will be staying on BBC Two until at least 18:30 BST (apologies, House of Games fans).

Coverage continues - whatever channel it's on - via the BBC Sport website and iPlayer.

Stephen Hendry
Seven-time world champion on BBC Two

The referee's got to get involved here, in my opinion.

Give the players three of give shots each, whatever.

Mark Allen and Wu Yize continue to nudge a red here and there as part of this stalemate.

It's more than 35 minutes since the last ball was potted.

One for the purists this.

Steve Sutcliffe
BBC Sport at the Crucible Theatre

With John Higgins and Shaun Murphy due to get back under way at 19:00 BST it appears extremely unlikely that the eight frames scheduled for this session will be played.

If the players are called off early those frames will be added to their final session on Saturday evening.

Careful with that black, now...

John Parrott
1991 world champion on BBC Two

There's a lot of snooker left in this frame unless there's a mistake and somebody knocks the black in. We aren't getting all the frames in - we might not even finish this one!

The safety exchange continues.

Mark Allen draws gasps from the Crucible crowd with a safety shot which sees a red brush the black which is lingering in the corner pocket.

Allen has 39 points while Wu has 13.

John Parrott
1991 world champion on BBC Two

This frame has the potential to go on for a long time. In fact with the way it is going they may not play the scheduled number of frames.

Image source, PA Media

The safety exchange between Mark Allen and Wu Yize has left most of the reds on the right side of the table, with the pocket which is loaded by the black more inaccessible.

Wu and Allen both foul attempting safety shots.

Could be a long frame this.

John Parrott
1991 world champion on BBC Two

You have frames like this where the black gets stuck in the jaws and the players get bogged down a bit. There's not much you can do unless a shot to nothing pops up. It just becomes awkward.