Carter lost to O'Sullivan in the 2008 and 2012 world finals, and suffered a similar fate in this second round match at Sheffield's Crucible Theatre.
He was forced to accept being second best in Monday evening's closing session despite doing little or nothing wrong as O'Sullivan moved onto a meeting with Stuart Bingham in the last eight after the Basildon player's 13-10 win over Mark Davis earlier in the day.
"It was another tough match and I was just pleased to have got through," said O'Sullivan.
"Anyone who says they're never uncomfortable out there is lying. Even last year there were quite a few times during the tournament where I thought it was slipping away from me, but you just have to stick in there.
"You've got to realise it's not a sprint it's a marathon and things can turn around at any point. You have to believe that you've got the ability if things do turn around, and stamp your authority on the frame. You have to stay with it and not get too worried when someone comes back at you.
"To have won the two matches that I've won and still be in the tournament is a bonus so to get another opportunity to play in a best of 25 at the Crucible is fantastic.
"I feel more burnt out now than I did last year. Last year the game was coming so easy to me that I could've played another 17 days after winning. I understand why people are saying it, but I only believe burnout comes when the game becomes difficult.
"If the game is easy and you find your fluency, I don't really believe burnout can happen. I played 15 or 16 tournaments coming into the World last year and felt fresher than ever, but I've had a year out and I've come to Sheffield and feel like I've played a mammoth season. I feel like I've just got off the plane from China."
A brilliant double on the final red up and down the length of the table in the 17th frame followed by a superb cut on a brown paved the way for O'Sullivan to move 10-7 clear.
Carter came up with a brilliant one-visit frame to reduce his arrears to 10-8 after a long red provided scope for a run of 86.
But O'Sullivan was not to be outdone as he pieced together 88 after Carter had missed a tricky long red from distance in trying to cut in the object ball.
O'Sullivan was flowing as we know he can and showed why he is favourite to defend the title he won last year with runs of 106 and 89 finishing Carter off in rapid style.
Carter had a rueful smile on his face at the end of the match as O'Sullivan continues along the road to a fifth Crucible title.
He is the first defending champion to reach the last eight since Shaun Murphy in 2006.
For the record, he has never lost to Carter in 15 career meetings.
"When he plays like that every time I play him, there's no wonder I haven't beaten him," commented Carter. "A lot of things happen out there that people don't see. Every time he goes into the reds he lands perfect on a ball, any little flick that can go wrong never goes wrong. But when you're playing well, that's what happens.
"I had him bang under it at 7-7. I shouldn't have taken on a long red, I should have perhaps played safe. But I was there to win, not to avoid defeat. If I could've got my nose in front who knows how he would've responded. It was a tough day today and he didn't do a lot wrong.
"If his head doesn't fall off then I think he'll win it. We all know if his head falls off that anyone can beat him. When he's playing like today then no-one can beat him. It makes no difference at all that he's been out for a year because he's been practising just like all the rest of us."
SECOND SESSION REPORT
Ronnie O'Sullivan produced some sublime snooker but was inconsistent in taking a 9-7 lead over Ali Carter after the second session of their World Championship last-16 match.
The Rocket was at his fluid best in recording breaks of 105, 86, 86, 73 and 61, but Carter's own break-building prowess saw him make three half-centuries to keep tabs on O'Sullivan who struggled with concentration in those losing frames.
The winner of the match will face either Stuart Bingham or Mark Davis in the quarter-finals and surely fancy their chances of reaching the last four from there.
O'Sullivan had the crowd excited immediately as he was on a maximum after four reds. That may sound ridiculous, but the pack was split and if there is a man who could make such an entrance, it is the four-times and defending champion. He left himself an awkward next red though potting his fourth black and opted for the blue before going on to record a smooth run of 86.
Carter refused a plant while in the forties in the second frame but a second visit of 74 ensured he kept within sight of O'Sullivan. The Captain has lost all 12 of his meetings with his fellow Essex player, including the World Championship finals last year and in 2008.
O'Sullivan has only played one tournament match since last year's victory in Sheffield, losing 4-3 to Simon Bedford at UKPTC3, and that may be a factor in his occasional lapses in concentration. Two such lapses in the next frame - a slight error in touching the cueball to the black then missing a pot - gave Carter the chance to build a lovely break of 87 up to the colours.
He missed again in frame 12, but a Carter defensive error let him back in and a liquid 105 clearance to the pink put him two frames up heading into the interval when it could easily have been 6-6. His ability to put together such runs when out of matchplay practice is highly impressive.
Again, however, he missed a black off its spot at 61-0 up and Carter - no slouch himself - responded with a 64 clearance when needing the black for 7-6.
Colchester cueman Carter potted with finesse in levelling, despite having bad luck with the cueball, but his accuracy left him as O'Sullivan fired in a 73 break - doubling a red with power before potting frame ball black. He then missed, but Carter surprisingly remained in his chair.
An 86 in the final frame of the session - courtesy of another double, to the delight of the fans, and again just before frame ball - puts him in control of the match. Despite his brilliance, doubts persist over his consistency over the length of this monster tournament as he seeks a 25th ranking title.
FIRST SESSION REPORT
Ronnie O'Sullivan impressed in spurts as he took a 5-3 lead over Ali Carter in their World Championship second-round match in Sheffield.
The Rocket, playing in his first major tournament since claiming his fourth Crucible crown last year, raced into a three-frame lead then hit a 125 break to go 5-1 up.
However Carter responded impressively in the final two frames of the session to remain firmly in this match.
O'Sullivan started slowly in the first frame but did enough to win it as Carter struggled with his safety play.
A brilliant 78 quickly extended his advantage - after missing the black off its spot at the start of the frame - and a 66 followed in frame three courtesy of shots taken with both hands. Carter responded with a 53 ahead of the interval to get on the board.
Carter took on a long straight red in frame five, missing it to let O'Sullivan in to win the frame, then after sitting through that 125 to the pink - leaving the black alone as it sat on the bottom cushion, despite having an angle to pot it - he must have feared the worst.
However a quick 82 run eased those concerns - he was on for a break in the 130s before missing a black - before the final frame of the session.
That was a defensive battle for the most part after both players held promising positions early on. Carter it was who built a careful half-century then just made it over the line as O'Sullivan sought the snookers he needed.
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