Result: Robert Milkins 10-9 Pang Junxu
End of session: Barry Hawkins 4-5 Ryan Day (first nine frames)
Result: Three-time champion Mark Williams beaten 10-9 by Si Jiahui
End of session: Mark Allen 7-2 Robbie Williams (resumes 14:30 BST Wed)
End of session: Ding Junhui 4-5 Jack Lisowski (resumes 10:00 Wed)
End of session: Kyren Wilson 8-1 Dominic Dale (resumes 10:00 Wed)
M Williams 6-8 Si
Stephen Hendry
Seven-time world champion on BBC Two
Just one or two signs, the first signs we've seen, of weakness from Si Jiahui.
These fractured frames will suit Mark Williams more than his opponent.
M Williams 6-8 Si
But Si misses, for him at least, a relatively straightforward red at 17 points each.
Becoming a huge frame this.
M Williams 6-8 Si
But the Welshman misses a much easier red, makes a mess of a safety shot and then almost trips up on the way back to his seat.
Another scrappy frame but a chance for Si to forge a few points ahead.
M Williams 6-8 Si
Another outrageous long red from Mark Williams, with the cue ball tucked tight on the baulk cushion no less.
Shot of the championship so far, reckons Dennis Taylor on commentary.
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Mokespoke: This is shaping up to be the match of the round.
M Williams 6-8 Si
Big error from Mark Williams early in frame 15.
Completely misses a thin clip on a red - and despite there being 15 reds on the table he somehow leaves a free ball, with the white's path to the reds obscured by baulk colours or pink.
However, a couple of shots later, Si smashes into the pack off the blue - and a red goes in to hand Williams four points and a return to the table.
M Williams 6-8 Si
Shaun Murphy
2005 world champion on BBC Two
They used to call Mark the best single-ball potter in the game and that's why.
An incredible shot. This match isn't over just yet.
M Williams 6-8 Si
John Parrott
1991 world champion on BBC Two
That is just obscene that red he knocked in.
M Williams 6-8 Si
This was the red Mark Williams took on to put that frame beyond Si.
The one to the right of the two together - crashed it into the green pocket.
Huge shot - and he thundered it in.
Image source, BBC SportAllen 3-1 R Williams
No change in the Mark Allen v Robbie Williams scoreline after the mid-session interval.
Allen leads 3-1 but we have a re-rack in the fifth frame.
M Williams 6-8 Si
Better signs for Mark Williams supporters now though, having got that cue back from the fan.
Shaun Murphy said Williams needed to make this match scrappier and he's done that, picking off his chances to leave Si Jiahui at the snookers required stage.
Just ran out of position on "frame-ball" red but crunched in a stunning long pot that got a rapturous round of applause from the Crucible crowd.
M Williams 5-8 Si
Mark Williams was so frustrated with his play earlier on, he handed his cue to a spectator!
Image source, PA MediaM Williams 5-8 Si
Referee Leo Scullion tells a spectator to put their sweets away.
Bit of a safety exchange going on after Mark Williams has accumulated a 39-0 lead in frame 14 - and clearly a member of the audience felt it was an opportune time to satiate their sweet tooth.
Williams, meanwhile, knocks in a sweet red to break the impasse. Big chance for the Welshman to get his first frame of the afternoon on the board.
Allen 3-1 R Williams
Michael Emons
BBC Sport at the Crucible Theatre
That last frame and a break of 86 will make Robbie Williams feel a lot better about himself.
After three successive first-round losses between 2014 and 2016 and then seven years of not qualifying for the Crucible, Williams said he wanted to show what he was really all about and perform on the big stage.
We just got a glimpse of that with that break, but a first-round draw against Mark Allen was one of the toughest he could've ended up with.
The Northern Irishman started off with a break of 70 and restricted Williams to only 36 points in all of the opening three frames to go 3-0 up, before the underdog pulled one back.
Obviously a long way to go, but Williams, the lowest-ranked player in the tournament at 45th in the world, will need to perform at his absolute best to stay in this one before this match concludes tomorrow afternoon.
Image source, Getty ImagesM Williams 5-8 Si
Signs of a slightly amended approach already as Mark Williams refuses to take many chances early doors in the first frame after the interval and both players agree to a re-rack.
Williams leaves Si a long red when the balls are racked up again - but it's off target and the white ball goes in instead.
But the Welshman can't really take advantage - after a red and blue he goes into the pack but lands on nothing.
M Williams 5-8 Si
Shaun Murphy
2005 world champion on BBC Two
We've seen Mark Williams enough, for long enough, that he will come out and try something different after the interval.
He won't play the same, no chance.
He'll have to drag him in the trenches now - if it goes to a toe-to-toe fight over potting balls, he's going to lose. We've seen enough from Si to know that.
He has to drag him under the water kicking and screaming, put balls on cushions.
Allen 3-1 R Williams
Eight frames on two tables this afternoon so far, and finally one has gone the way of a Williams.
Robbie knocks in a break of 86 to head into the mid-session interval 3-1 down against Mark Allen.
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Image source, PA MediaShould the tournament stay or move from the Crucible Who will win? What's the state of the game right now?
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Former world champion Neil Robertson has defended Hossein Vafaei, who himself was criticised after criticising the Crucible venue (see post at 15:04)
Robertson wrote on X: "Some of the comments towards what Hossein Vafaei said regarding the Crucible, which are all true (maybe not the smell part) is really disappointing.
"We’ve seen far worse comments from British-based players about the same venue and others that were laughed off or swept under the carpet by those who put their boot into him.
"This is a guy btw who I’ve seen play matches with no sleep for 30 hours because he’s had to travel through multiple different countries just to get a visa in time. He has it the hardest on tour by a mile"
Here's the top 16 seeds - those in bold are out
1. Luca Brecel, 2. Ronnie O'Sullivan, 3. Judd Trump, 4. Mark Allen, 5. Mark Selby, 6. Mark Williams, 7. Ding Junhui, 8. Shaun Murphy
9. Ali Carter,10. Gary Wilson, 11. Zhang Anda, 12. Kyren Wilson, 13. John Higgins, 14. Tom Ford, 15. Barry Hawkins, 16. Robert Milkins