Singh, 52, narrowly missed a nine-foot putt for eagle on his final hole, the par-five ninth, as he ended a bogey-free display with consecutive birdies for a three-way tie at the top after taking advantage of relatively benign morning conditions.
"I was feeling good about my body, my swing, my mind, so I just went out there -- it was early -- started off well and just kept it going," Singh told Golf Channel after making his 19th career start at the event.
"I scrambled very well. Early on, I didn't hit too many fairways but I got it around the greens, chipped in once and my putter was working really well."
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South Korea's Kim Si-woo carded a 64 in the PGA Tour's first full-field event of the year while another former world number one, England's Luke Donald, was among six players who opened with 65s.
Level with Donald were Americans Sean O'Hair, Shane Bertsch, Zac Blair and 2002 Sony Open champion Jerry Kelly, and Canadian David Hearn.
Singh, a 34-times winner on the PGA Tour, has in recent years battled assorted health problems which impacted his trademark loose-limbed swing but he still believes he is capable of winning at the game's highest level.
"I just want to play," he replied when asked what kept motivating him as one of the PGA Tour veterans. "I feel like I can come out and win any tournament if I play well. It's been the same way for the last five, six years.
"I just haven't produced the scores that I want to produce, but I'm always optimistic about my next day, my next round, my next tournament. Same this year," added Singh, who has long been renowned for his workaholic approach to practice.
Reigning champion Jimmy Walker, who is bidding this week for an unprecedented third victory in a row at Waialae, was among the late starters on Thursday.
(Reporting by Mark Lamport-Stokes in Los Angeles; Editing by Frank Pingue)
