Seamus Power's blistering recent form continued at the AT&T Pebble Beach Pro-Am after he signed for a round of 64 to sit just one shot off the lead.
Tom Hoge strung together six birdies in a row near the end of his round to post a nine-under 63 and take the first-round lead.
The 32-year-old leads Power by one stroke, with Austin Smotherman and Sweden's Jonas Blixt tied for third at 7 under.
Power's bogey-free, eight-under 64 came at the Spyglass Hill course.
Everyone in the field will play one round apiece at Pebble Beach, Spyglass Hill and Monterey Peninsula before Pebble Beach hosts the final round following a 54-hole cut.
The Irishman wrapped up the round with four straight birdies on the front nine.
"It's a funny old golf course," Power said. "I hit a horrible tee shot on the par-three fifth, had a very good up-and-down to kind of stay at four (under) and then just kind of clicked coming in, really, made a couple of very nice putts and a couple of very nice shots."
Ireland's other representative at the tournament did not fare so well and John Murphy is on three over after his round of 75 at Spyglass Hill.
Hoge pulled off his low round at the tournament's primary course, Pebble Beach Golf Links.
Hoge started on the back nine and opened with two birdies before arriving at the tee at number three just three under for the round. That's where he began his birdie run, which featured a chip-in at the par-four fourth hole and a 40-foot putt at the par-four eighth.
"It's hard to be in a bad mood out here," Hoge said. "I mean, Pebble Beach and perfect weather is about as good as it gets... I feel like I've been playing well. I've been excited to get out here on the golf course and feel like at Pebble Beach is a golf course that suits me well, so I was excited to get out here this week."
Though still searching for his first PGA Tour win, Hoge has two top-five finishes this season, including second two weeks ago at The American Express.
Patrick Cantlay, the reigning FedEx Cup champion and highest-ranked player in the field, carded a six-under 65 at Monterey Peninsula, tying him with Andrew Putnam for fifth.
Cantlay made three birdies over his first six holes, fell back with consecutive bogeys at the seventh and eighth and recovered with five birdies on the back nine, including the last three holes.
"I think that you definitely need to do your scoring here, and depending upon how Spyglass is set up that could be really tough with the greens being bouncy, but if you look at the scores, year after year, they're always high teens," Cantlay said.
Defending champion Daniel Berger withdrew Wednesday before the tournamentbegan due to a back injury.
