Woods near last after opening 75 at Northern Trust

Tiger Woods joked that at least he broke 80 after struggling to a four-over-par 75 in the first round at the Northern Trust in New Jersey on Thursday.

The score was the latest indication that all is not well with the 15-times major champion's surgically-fused spine, though his putter also let him down at Liberty National in perfect morning conditions.

Woods acknowledged that his back was stiff on the eve of the first event of the PGA Tour's FedEx Cup playoffs.

"It's still a little bit stiff, but that's just the way it's going to be," he told reporters after finishing nearly last on a morning when Troy Merritt shot 62 to lead fellow American Dustin Johnson by one shot with half the field having completed their rounds.

Woods could barely have made a worse start, four over par after nine holes, before somewhat steadying the ship on the back nine.

"I didn't hit any good shots and didn't make any putts. Other than that it added up to a round that broke 80," Woods said.

"The driver felt fine but I just didn't feel sharp with anything else. My iron game, which is usually the strongest part of my game, was off ... my distance control was off."

Since ending a decade-long major drought by winning the Masters four months ago, 43-year-old Woods has barely played outside the majors and has not impressed when he has competed.

He entered this week's event ranked 28th in the FedEx Cup rankings.

Even if he misses the cut on Friday, he is assured of advancing to next week's BMW Championship, but not to the season-ending Tour Championship, where he won last year in a rousing performance that set the stage for his Masters triumph.

"I knew I had to post a low one and just didn't do it," Woods said. "We had an early tee time, perfect greens.

"It just feels frustrating to shoot anything high no matter how I feel. I'm going to have to figure out a way to get this thing under par (on Friday)."

JOHNSON FINISHES STRONGLY

While Woods looked a pale shadow of his former self, recent world number one Johnson was near his best, particularly towards the end as he reeled off four straight birdies from his 14th hole.

Even Johnson's worst drive of the day, at the par-four seventh, turned out well.

"I actually hit it into sixth fairway and it worked out fine and I ended up making birdie," he said.

"Golf course is soft. I had a lot of nice looks at birdie and rolled it really well too."

Merritt "half-shanked" his opening tee shot, but sank a 10-footer to save par and, suitably buoyed by the reprieve, ran in birdies at the next four holes.

"It's nice to see putts go in early, especially from a little bit of length," he said after a nine-birdie round.

"It gives you confidence the rest of the day and they just kept going in."

Merritt, a two-times PGA Tour winner, is 72nd in the standings and in need of a solid finish to advance to next week.