Sahith Theegala fired an eight-under-par 64 to grab a share of the lead at the halfway stage of the PGA Tour's Fortinet Championship in Napa, northern California on Friday.
The world number 37 reeled off seven birdies and an eagle to surge to 12 under after 36 holes, with South Korea's Kim Seong-hyeon joining him at the top of the leaderboard after a five-under-par 67.
In perfect conditions at the Silverado Resort's north course, Theegala relied on a red-hot putter and some superb approach play to march up the leaderboard.
Theegala and Kim lead by one shot from South Korea's Bae Sang-moon, who is a shot back on 11 under after a six-under-par 66.
Eric Cole, who also shot a 66, is a further shot back on 10 under, two off the lead.
But the low round of the day belonged to Theegala, who made a blistering start with back-to-back 10-foot putts yielding birdies on his third and fourth holes.
He nailed a chip from 48 feet to within two feet of the hole for another birdie on his sixth hole before giving up that shot with a bogey on his seventh.
He made amends just before the turn, when he drilled a 47-yard approach shot to four feet for a simple tap-in birdie.
A monster 48-foot birdie putt on his 11th hole took him to four under for the round, and he then chipped in from a greenside bunker on the par-five fifth, his 14th hole, for an eagle three that took him to six under.
Two more birdies down the stretch followed to leave Theegala firmly in the hunt for his first individual PGA Tour title.
"It was a great round," Theegala said afterward. "It was one of those rounds where I just felt like I needed to give myself chances and if I did, I had a good chance of making it."
Theegala will go into the third round aiming to break clear of co-leader Kim, who shot six birdies and a bogey en route to his 67.
With Kelly Kraft three off the pace on nine under after shooting a 69, a cluster of five players are four off the lead on eight under.
They include Justin Thomas, who showed signs that he is returning to form just in time for this month's Ryder Cup with a five-under-par 67 that included back-to-back birdies on his final two holes.
"I played well, I played really solid, I drove the ball well, felt like I gave myself a lot of chances," Thomas said.
"It was nice to make those putts on the last two holes ... that's why I stay patient, just kind of stay in it and was able to birdie those last two to salvage a good round."
rcw/tjj
