Louisville - Tiger Woods was nowhere to be seen Tuesday at the PGA Championship, except for his image on promotional banners, and his status for Thursday's scheduled start at Valhalla remained uncertain.
Former world number one Woods, a 14-time major champion chasing the record 18 majors won by Jack Nicklaus, suffered a back injury Sunday during his final round at the World Golf Championships event in Akron, Ohio.
Woods, who underwent back surgery March 31 to ease a pinched nerve, returned in late June and missed the cut at a PGA event his foundation owns, then shared 69th, his career worst 72-hole major showing, at last month's British Open.
Woods has not finished 72 holes in a US event this year without pain, going the distance only at Doral in March with a final-round 78 when he struggled to bend a collected his ball from the cup and grimaced at times after shots.
It's a far cry from the level Woods played in the 2000 PGA Championship at Valhalla, when he beat Bob May in a playoff to win the third leg of what would be four major titles in a row - the "Tiger Slam."
From his record-shattering first major title at the 1997 Masters to his most recent major crown at the 2008 US Open when he limped to a playoff victory over Rocco Mediate, Woods has attracted fans beyond golf devotees to the sport.
"The dominance of Tiger's play over a 10-year period is unmatched, really, I would have to say and was quite incredible," said Adam Scott, who in May dethroned idled Woods from the world number one spot.
Since his last major win, Woods has been nagged by a series of injuries to his back, knees and legs.
But if he fails to play this week, it would mark the first time in his career he has missed three majors in a season, having sat out the Masters and US Open this year while recovering from surgery.
Woods, ranked 10th, had not registered with PGA officials by Tuesday afternoon but could still do so just before his Thursday morning tee time and play in the year's final major.
Woods, who will turn 39 in December, is slated to play the first two rounds alongside five-time major winner Phil Mickelson and Ireland's Padraig Harrington.
American Shawn Stefani had been atop the alternates list, but qualified for his first PGA Championship late Tuesday when tournament officials announced American David Toms had withdrawn.
That moved American John Huh into position to be the man to enter the field of 156 should Woods withdraw.
The PGA Championship remains listed as Woods' next event on his website.Rivals spoke with concern about Woods' condition more than fear of him capturing a fifth Wanamaker Trophy.
Reigning US Open champion Martin Kaymer of Germany played alongside Woods in the first two days at Akron and was impressed with Woods' chipping.
"Everybody wants him to be back at the golf tournaments," Kaymer said Tuesday. "If you win a big tournament without Tiger in the field, you still feel very happy about it, but you want to play against him. It's nice if he's part of every tournament. He brings a lot of people into it. It has a different flair."
Kaymer said he would have made certain not to return too soon from surgery, Woods having said in June he had been cleared to begin playing just before entering his PGA event.
"If I had injuries like this, I would probably make really, really sure that I'm healthy, because he's 38 years old, so hopefully he will have another 10 to 15 years of competing."
Masters winner Bubba Watson, told that Las Vegas bookmakers still listed him alongside Woods with 33-to-1 odds of winning, said, "I don't gamble but if I did I would always pick Tiger Woods."
"He had surgery on his back, so let's just give him a little time. He'll be back to Tiger Woods."
Woods called the pain he felt before the surgery so debilitating that at times he could not get out of bed.
"Obviously this is a serious issue he is dealing with," Watson said. "It's unfortunate. He grows the game. He moves the needle more than anybody else."