Ronnie O'Sullivan has apologised to the Alexandra Palace crowd following his Masters win over Barry Hawkins on Thursday.
The Rocket also felt sorry for his opponent after admitting he 'dragged him down' to an 'awful' level of snooker.
O'Sullivan won 6-3 to progress to Saturday's semi-final, where he will play either Shaun Murphy or Jack Lisowski.
The 48-year-old was not at the top of his game but had enough to see off Hawkins as he continues his hunt for a record-extending eighth title.
Ronnie O'Sullivan apologised following his win over Barry Hawkins
BBC
Hawkins led 3-2 at one point but O'Sullivan, has he so often has done, found a way to get the job done.
But he admitted afterwards that he felt he was 'lucky' to progress to the last four at Ally Pally.
O'Sullivan said: "I just feel sorry for Barry.
"He was playing good until he started playing me and I just dragged him down to probably the most awful standard of snooker.
"So I'm really sorry about that today but I'm just lucky to get through really, that's all I can say."
O'Sullivan pulled off an audacious shot on the red to set up his victory.
He admitted he had to take the gamble as he may not have got another opportunity to win.
The Rocket added: "Yeah I knew when I got that chance, if I had a shot I was just going to go for it because you might not get another chance.
"I know it was a tough red but sometimes you've just got to take the tough ones on, you know."
O'Sullivan, who beat Ding-Junhui in his first match at the tournament, will discover his semi-final opponent on Thursday night.
2005 world champion Murphy will be hoping to make it through against Lisowski.
Murphy claimed recently that O'Sullivan is the greatest snooker player he has ever seen.
The 41-year-old told the BBC: He said: "I feel safe these days with the word I'm about to write: GOAT.
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Ronnie O'Sullivan admitted he was not at his best against Barry Hawkins
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"He's had more wins, he has earned more money and had more centuries than any other player. I don't think you can make the argument any more.
"He's incredible to watch. It's almost like he challenges himself when he's out there.
"Almost like this game is too easy. Almost like he wants to play the game in its purist form.
"He would have been just splashing the reds, and clearing up years ago.
Ronnie O'Sullivan beat Barry Hawkins 6-3 at the Masters
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"I think the challenge aspect keeps his focus. We didn't think your century record would be beaten, but he's closing in on twice as many and is well into the 1200s.
"Incredible break-builder, incredible long potter and of course, we go back to when he teamed with Reardon all those years ago, and he did become the complete player."