The 46-year-old hit breaks of 71 and 126 in the first two frames of the morning session to overtake Stephen Hendry's record of reaching the last four.
O'Sullivan - who is aiming to emulate Hendry's record of seven world titles - said the Scot was the Tiger Woods of snooker during his decade of dominance in the 1990s.
"Stephen is an all-time legend for me, the greatest player," O'Sullivan said after his win over Stephen Maguire.
"He was the Tiger Woods of snooker. Me, John (Higgins) and Mark (Williams) have all done well, but when he was flying he was a superstar.
"When there's three of us, we're not superstars. But when there's one man dominating the sport like he did, like Tiger Woods, it's a different level."
O'Sullivan had carved a commanding lead despite never quite hitting top form against Scottish qualifier Maguire on Tuesday, but showed glimpses of his best upon the resumption.
O'Sullivan has now beat Dave Gilbert and former semi-finalist Mark Allen alongside Maguire and will now play either Higgins or Jack Lisowski in the last four.
Talking about his performances so far, O'Sullivan described them as 'workmanlike' but said he will be able 'relax' now that his next match is on one table in the venue.
"It's workmanlike more than flowing, but I've had to learn to steady the ship and I think that's the key to being consistent - being able to minimise the bad spells," said O'Sullivan.
"I am looking forward to it. When it comes to the one-table set-up you can relax a bit more, and I'm excited still to be in the tournament and to get there."
Judd Trump and Stuart Bingham will resume their quarter-final level at 8-8 on Wednesday evening after a topsy-turvy second session.
Resuming 5-3 behind, Bingham reeled off the first five frames of the day to lead 8-5 and leave a distinctly out-of-sorts Trump facing the prospect of a significant deficit.
But a missed black off the spot in the next by Bingham proved pivotal, as Trump dredged up a break of 41 to take the frame, then won the next with a break of 89.
With the momentum swinging back in Trump's favour, Bingham, who had himself struggled to sustain any kind of consistency, was punished for missing a red in the final frame of the session, enabling Trump to pull level.