Augusta - Tiger Woods returned to Augusta National with a one-over par 73 that he said was enough to keep him in the mix in his first Masters in three years.
"Seventy-three is fine," Woods said. "It's really hard to run away from it, but it's also really easy to lose it out there.
"By the end of the week there will be a bunch of guys with a chance to win this tournament."
Woods, who calls himself a walking miracle less than 12 months after spinal fusion surgery, produced a pair of top-five finishes on the PGA Tour this year to fuel expectations that he could seize a fifth green jacket - and a 15th major title - this week.
"It has been awesome this entire comeback," Woods said. "I got a standing ovation on the range. Coming up to the first tee, the people come out of the clubhouse and the putting green, they're really into it."
The 14-time major winner thrilled an enthusiastic gallery with a delicate, downhill birdie putt at the third.
But he followed with back-to-back bogeys at the fourth and fifth as he made the turn one-over.
There was more trouble lurking around Amen Corner, where Woods was right off the tee at 11 and his shot from the trees hit a fan and dropped into the rough.
"It was a great shot there," said Woods, who ended up with a bogey. "Unfortunately people ran out and it clipped them. Otherwise it's just short right of the green, an easy up and down from there, where I was trying to leave it."
A dip in Rae's Creek at 12 cost him a shot, although that could have been worse. Woods rolled in an impressive 18-footer to limit the damage.
He pulled strokes back at 14 and 16 and produced two crisp tee shots at 17 and 18 as he capped his round with a pair of solid pars.
"I could have easily let it slip away. And I fought hard to get it back and I'm back in this championship," said Woods, who carded a first-round 74 in 2005 on the way to his most recent Masters title.
Australian Marc Leishman played alongside Woods and topped the leaderboard at four-under before finding the water at 15 on the way to a double bogey.
"We had a good day out there," said Leishman, who shot 70.
"I looked at it as a positive and preparation for later in the week," he said of playing with Woods. "Hopefully we're both there on Sunday afternoon."
Complete first-round scores on Thursday from the 82nd Masters at par-72 Augusta National Golf Club (a- denotes amateur):
66 - Jordan Spieth (USA)
68 - Tony Finau (USA), Matt Kuchar (USA)
69 - Adam Hadwin (CAN), Li Haotong (CHN), Henrik Stenson (SWE), Charley Hoffman (USA), Patrick Reed (USA), Rory McIlroy (NIR), Rafael Cabrera Bello (ESP)
70 - Bernd Wiesberger (AUT), Zach Johnson (USA), Marc Leishman (AUS), Phil Mickelson (USA), Rickie Fowler (USA)
71 - Vijay Singh (FIJ), Satoshi Kodaira (JPN), Cameron Smith (AUS), Xander Schauffele (USA), Louis Oosthuizen (RSA)
72 - Francesco Molinari (ITA), Kyle Stanley (USA), Charl Schwartzel (RSA), a-Doug Ghim (USA), Fred Couples (USA), Kevin Kisner (USA) Tommy Fleetwood (ENG), Justin Rose (ENG)
73 - Ted Potter Jr. (USA), Brian Harman (USA), Daniel Berger (USA), Pat Perez (USA), Jason Dufner (USA), Hideki Matsuyama (JPN), Branden Grace (RSA), Tiger Woods (USA), Bubba Watson (USA), Jimmy Walker (USA), Russell Henley (USA), Thomas Pieters (BEL), Dustin Johnson (USA)
74 - Austin Cook (USA), Wesley Bryan (USA), Ryan Moore (USA), Jose Maria Olazabal (ESP), Bryson DeChambeau (USA), Paul Casey (ENG), Martin Kaymer (GER), Justin Thomas (USA), Sandy Lyle (SCO), Ian Poulter (ENG), Bernhard Langer (GER), Tyrrell Hatton (ENG), Alex Noren (SWE)
75 - Jason Day (AUS), Kim Si-woo (KOR), Patrick Cantlay (USA), Matthew Fitzpatrick (ENG), Danny Willett (ENG), Adam Scott (AUS), Jon Rahm (ESP)
76 - Angel Cabrera (ARG), Mike Weir (CAN), a-Joaquin Niemann (CHI), Yuta Ikeda (JPN), Brendan Steele (USA), Patton Kizzire (USA), a-Doc Redman (USA), Billy Horschel (USA), Chez Reavie (USA), Larry Mize (USA), Webb Simpson (USA)
77 - Shubhankar Sharma (IND), Dylan Frittelli (RSA), Kevin Chappell (USA), Jhonattan Vegas (VEN), Yusaku Miyazato (JPN)
78 - Trevor Immelman (RSA), Mark O'Meara (USA), Ross Fisher (ENG), Gary Woodland (USA)
79 - Lin Yuxin (CHN), Ian Woosnam (WAL), Kiradech Aphibarnrat (THA)
81 - Sergio Garcia (ESP), a-Matt Parziale (USA)
86 - a-Harry Ellis (ENG)