Ronnie O'Sullivan could face potential sanctions after WST officials said they were "aware" of a gesture he made at the World Championships.
O'Sullivan, who is chasing what would be a record-equalling seventh title, beat David Gilbert 10-5 in his opening round match.
However, in the 13th frame, after missing a black off its spot, O'Sullivan appeared to make a lewd gesture as he returned to his seat.
It could leave the Rocket with a possible fine should it be deemed sufficiently serious to bring the sport into disrepute.
"We are aware of the incident and it has been referred to the WPBSA disciplinary committee," a World Snooker Tour spokesperson said.
O'Sullivan will play Mark Allen next following the Northern Irishman's 10-6 success against Scott Donaldson.
Allen, though, was far from happy with the quality of the table.
"I struggled a little bit with the table," Allen told Eurosport. "It wasn't the best I've ever played on. It actually got worse as the day went on.
"Me and Scott both had to speak to the ref to see if it was the same set of balls this evening because the table played completely different.
"It was tough. It doesn't lend itself to the prettiest of snooker when you're getting big bounces and scared of when it's going to come.
"To make it 2-2, I felt I got out of jail a little bit because he was by far the better player at that point.
"Scott was getting on top, real good safety and I had a lot of awkward shots. I was just hanging in there.
"I had to find a bit of form because I didn't think I had much at the start.
"I controlled it from there, but there were still one or two mistakes which you can't afford to be making."
Former world champion Mark Williams also progressed to round two, beating Michael White 10-3.
Meanwhile, former Crucible winners Mark Bingham and Neil Robertson both command 6-3 leads going into Wednesday against Lyu Haotian and Ashley Hugill respectively.