'The Rocket' was again at his dominant best in the quarter-final to beat Stephen Maguire 13-5, meaning he has now made it into the final four for a record 13th time. That win was preceded by wins over David Gilbert and Mark Allen, meaning O'Sullivan has also now overtaken Stephen Hendry for the most number of wins at The Crucible.
In true O'Sullivan style though, it's not just his performances which have made an impact. During his first-round game with Gilbert, following an error, the man from Essex appeared to mime masturbation as he walked around the table.
In his semi-final clash he'll face John Higgins, a match which has the potential to be feisty after the Scot labelled O'Sullivan a "disgrace" for publicly saying he'd tell his son not to play snooker. But rewind back to 2015, and the six-time champion was in the news for another dubious matter.
O'Sullivan, 46, opted to put chalk on the table to help line up a shot during his quarter-final match with Stuart Bingham. That should have meant a seven-point penalty, with under snooker rules, occurs when a player 'uses any object to measure gaps or distance'.
He got lucky though, with referee Terry Camilleri opting not to reprimand him. In fact it was commentator Ken Doherty, himself a former world champion, who picked up on the discrepancy.
Did you know putting chalk on the table carries a seven-point penalty? Let us know in the comments section.
Perhaps justice was done though as Bingham eventually upset the odds, winning the match 13-9. The 50-1 outsider would go on to claim his only world crown, beating Shaun Murphy 18-15 in the final.
Indeed, the 2015 tournament proved a busy one for O'Sullivan. He escaped a fine after briefly playing in his socks in his first-round win over qualifier Craig Steadman - then came close to snapping his cue during his second-round match against Matthew Stevens.
Regardless, the 46-year-old has another title within his grasp this year. If he prevails against Higgins, also 46, he'll play the winner of Mark Williams and Judd Trump.