Now, barring a miracle in the final round of the US PGA Championship at Oak Hill, 18 is also the number of majors he will have played since his last victory in the 2008 US Open.
Woods had come into the final major of the year fresh from shooting a second-round 61 en route to winning an eighth Bridgestone Invitational by seven shots on Sunday, his fifth victory this season.
But he struggled to a third round of 73 on Saturday to finish four over par, just as halfway leader Jason Dufner was heading to the first tee.
The 37-year-old found heavy rough from the first tee and from there hooked his second shot into a tree some 50 yards in front of him. He was lucky to see the ball bounce back into the fairway, but then played a poor pitch to 15ft and left his par putt well short of the hole.
Woods also bogeyed the third after missing the green and failing to get up and down, but at least saved par after bad drives on the fourth and ninth and birdied the 11th - only his seventh birdie of the week.
Two more bogeys followed on the 16th and 17th and left Woods facing up to a fifth straight year without a major.
Asked to sum up his week, Woods said: "Not joyous, that's for sure. It's just one of those weeks where I didn't quite hit it well enough and didn't make enough putts. That's golf. We don't play well every week."
He denied he was trying too hard in majors, adding: "As far as that's concerned, no. As far as overall game plan and the way I'm playing, I've been there in enough of these things where I've been right there in the back nine on Sunday with a chance."
World number two Phil Mickelson fared even worse, the Open champion carding a 78 that equalled his highest ever score in the US PGA and left him 10 over par and 74th of the 75 players to make the cut.