Miami - Tiger Woods rolled in six birdies, including a 71-footer at the seventh hole, to leap into contention on Thursday at the Arnold Palmer Invitational led by Henrik Stenson.
Woods, the 14-time major champion and eight-time winner at Bay Hill, started early and showed the peak form that sparked his best finish in five years last week.
"It was just getting a feel for playing tournament golf again and I think I have it," said Woods, who is playing the fifth US PGA Tour event since returning in January from spinal fusion surgery last April.
"I'm not thinking as much around the golf course. I can just see it, feel it and go. That's because I've got my 'feels' back."
Three weeks before the start of the Masters, the year's first major tournament, Woods showed none of the back pain that sidelined him most of the past two seasons. He has undergone four back operations, doubting at one stage if he would ever return to competitive golf.
"I enjoy just playing again. After what I've been through, just playing feels good," Woods said.
Told that Las Vegas oddsmakers were making him the Masters favourite based on his past week's performance, Woods said, "A lot of gamble-holics out there."
"We have a long way to go. It's just the first day. I've got three days to go and hopefully I can cap it off with a nice win."
Sweden's Stenson made nine birdies against a lone bogey to open with a 64.
American rookies Aaron Wise and Talor Gooch were tied for second on 65.
Jimmy Walker, the 2016 PGA Championship winner, holed out from 132 yards for an eagle on the 18th fairway to complete an opening 67 that left him tied with Rickie Fowler and Bryson DeChambeau, one stroke ahead of Woods.
Four-time major winner Rory McIlroy was set to match Walker and Fowler but closed with a double-bogey to finish on 69.
The day's electricity came from Woods, the 42-year-old superstar who has not won a major since the 2008 US Open and hasn't captured any title since the 2013 World Golf Championships Bridgestone Invitational.
Woods, who also won his eighth Bay Hill crown in 2013, birdied all four par-5 holes and played the rest of the round at level par, two birdies undone by one bad tee shot and a double-bogey disaster.
"People have been so supportive. It has been a great atmosphere overall since I've come back and started playing again," Woods said.
Woods, whose 79 career PGA titles are three shy of Sam Snead's career record, began on the back nine and sank a 10-foot birdie putt at the par-5 12th. He followed with a 17-foot birdie putt at the par-4 13th and dropped in a six-footer for birdie at the par-5 16th.
At the par-3 second, Woods found a bunker but blasted out inches from the cup to save par. He stumbled on his next swing, sending his tee shot way right and out of bounds on the third hole on his way to a double-bogey six.
But Woods responded with birdies on three of the next four holes, sinking a four-footer at the par-5 fourth and a three-footer at the par-5 sixth.
That set the stage for his greatest putt of all. On the far edge of the seventh green, Woods curled the ball to the right, watched it pick up speed and roll into the cup from 71 feet for a birdie that brought a smile to his face and a raised hand to acknowledge the crowd's cheers.
"I just wanted to get down in two. I didn't want to drop another shot," Woods said. "I'm lucky it hit the hole or it was probably eight feet by."
But the work wasn't over. At his final hole, the par-4 ninth, Woods found a greenside bunker and blasted out 11 feet past the cup, then sank the clutch par putt.
Leading first-round scores on Thursday in the PGA Tour's Arnold Palmer Invitational at Bay Hill (USA unless noted, par 72):
64 - Henrik Stenson (SWE)
65 - Aaron Wise, Talor Gooch
67 - Jimmy Walker, Rickie Fowler, Bryson DeChambeau
68 - Patrick Reed, Tiger Woods, An Byeong-Hun (KOR), Billy Horschel, Brian Harman, J.B. Holmes
- Brandon Harkins, Justin Rose (ENG), Graeme McDowell (NIR), Zach
Johnson, Tommy Fleetwood (ENG), Rory McIlroy (NIR), Emiliano Grillo
(ARG), Ernie Els (RSA), Sam Burns
70 - Bubba Watson, William
McGirt, Hideki Matsuyama (JPN), Ryan Armour, Paul Goydos, Marc Leishman
(AUS), Matt Every, Tyrrell Hatton (ENG), Kevin Chappell, Sam Horsfield