|Venue: Crucible Theatre, Sheffield Dates: 31 July-16 August
|Coverage: Watch live on BBC One, BBC Two, BBC Four and Red Button, with uninterrupted coverage on BBC iPlayer, BBC Sport website and BBC Sport app. Full details and times.
Qualifiers Jamie Clarke and Anthony McGill were involved in a feisty exchange at the World Championship, with the referee having to step in to calm the situation.
Scot McGill was unhappy with his Welsh opponent for apparently standing in his line of sight while down on a shot.
McGill, who trails 8-4 in the second-round match, made his feelings known to both Clarke and official Jan Verhaas.
Five-time champion Ronnie O’Sullivan is level at 8-8 against Ding Junhui.
The pair were all square at 4-4 after the first session, but China’s Ding pulled ahead with three frames in a row.
O’Sullivan hit back with breaks of 90, 89 and 73, but 2017 runner-up Ding’s 53 makes it a fascinating encounter heading into Sunday’s conclusion at 19:00 BST.
‘A nasty moment’ – what happened between McGill and Clarke?
In the 10th frame Clarke, the lowest ranked player in the tournament, played a safety shot on the yellow and instead of making his way back to his seat, stood at the opposite end of the table.
McGill was unhappy with his opponent standing in his line of sight on his shot and walked up to explain the situation to Clarke, before Verhaas intervened by saying, “leave it, leave it”.
McGill said it was “no big deal” but was visibly angry at the incident and his mood will not have improved as he watched his opponent clear up the table to win the frame by two points.
Clarke left the arena after winning the frame and McGill quickly followed by running after him.
On their return, Dutch official Verhaas said to Clarke: “The rule clearly officially states you have to avoid being in the eye-line of the player.
“If he is playing in that direction then I would like you to be in your chair and sit down.”
Six-time world champion Steve Davis called it a “nasty moment” while 1991 world champion John Parrott said on BBC Two: “I have not seen many [scenes] like that, it is quite heated.
“It is a very small and tight venue when there are two tables and you can get trapped. If you have played your shot and cannot get back to your seat, then as a courtesy you will stay at the other end of the table and hopefully be out of the way.
“If it is continually happening and Anthony feels he is in his eye line then he is perfectly entitled to say something. It does not help being 7-2 down so is not in the best of moods.”
Kyren Wilson took a first-session lead against Martin Gould as he finally began his campaign after being granted a bye into the second round.
Englishman Wilson, who progressed after Anthony Hamilton’s withdrawal, racked up breaks of 52, 113, 63, 90, 64 to lead compatriot Gould 5-3.
Meanwhile, Neil Robertson recovered from spilling coffee over himself to go 5-3 up against Barry Hawkins.
The Australian spilt the hot drink on his trousers before his opponent sat in the wrong chair, in what were arguably the highlights of their opening exchanges.
Both matches resume at 19:00 BST.