After sinking the long putt, the defending champion pumped his fist as a large gallery following him, two-time champ Ernie Els and U.S. Amateur winner Ricky Barnes broke into a loud ovation.
Woods, playing holes 10-18 first, had a bogey on the 18th and another at his last hole - No. 9 -on the 7,190-yard course at Olympia Fields.
"I didn't hit a few tee shots the way I wanted," Woods said. "You have to be patient, the golf course will only get tougher. In a major championship, you just have to keep plugging away."
Woods was four shots behind Justin Leonard, who had three straight birdies from 13-15 and finished 4-under 66.
Among other early starters near the top were Australian Stephen Leaney, who shot had a 3-under 67, and Tom Gillis and Ian Leggatt, who were at 68. Els finished with a 69.
At the start, Woods hardly looked like the player who won two of the last three U.S. Opens, on a cloudy and cool 60-degree morning.
Woods was in the right rough on No. 12, in the left rough on No. 14, but managed to keep par in the picture with skillful irons that bounced onto the firm greens.
He finally paid for it on the 18th, hitting his 3-wood into the bunker and, with his feet anchored in thick grass, hit a low punch into the deep collar of rough surrounding a bunker left of the green. He chopped it out to 15 feet and then 2-putted.
The course is a typical U.S. Open layout, featuring tough roughs, deep bunkers and quick greens. That's why low scores aren't expected.
With the exception of Woods at Pebble Beach three years ago - a record 12-under 272 - the U.S. Open champion has been no better than 5 under since 1994.
Will the rest of 155 players in the 103rd Open be chasing Tiger, who has won three tournaments this year but none since Bay Hill in March?
That field includes Davis Love III, who is enjoying his best season in 11 years with three victories, including The Players Championship.
And Vijay Singh, who has five top 10s in his last six tournaments and a victory in the Byron Nelson Classic.
How about Kenny Perry, the hottest player on tour with back-to-back wins at the Colonial and the Memorial before taking a week off?
Or might this be the week Phil Mickelson - winless this year - breaks through and ends his 0-for-43 drought as a pro in the majors?
Els won the U.S Open at Oakmont in 1994, beating Loren Roberts and Colin Montgomerie in a tense three-way playoff. He was victorious again three years later at Congressional.
"There are two times I can think about pressure. Oakmont was probably the most I ever felt in my life," Els said. "And then obviously at Congressional. I had to make a 4- or 5-footer on the 18th to win.
"Don't get me wrong. There is pressure in each and every event, but the majors mean so much more to us as players. And sometimes we get in our own way."
Els has answered his fair share of Tiger-related questions over the years, but says beating Woods is not his main motivation. Winning is.
"I'm sure younger guys come out and they want to beat Tiger. Tiger is going to beat us 70 percent of the time, so in that way they're right," Els said.
"I've got certain goals I want to achieve in my career and hopefully I don't have to go through Tiger. If he's there, you've got to do what you have to do."
Barnes was paired with Woods at the Masters and knows what to expect with the hordes of spectators at every turn.
"Most of the golf fans, because of the Masters and playing with Tiger, recognize me," Barnes said.
"That's cool and nice that they know your name."
But Barnes promises his opening round won't be a personal gawking session, even though he'll be matching shots with two of the world's greatest players. He ended up with a 1-over 71.
"I've got the course to tame," he said. "Not Tiger or Ernie."