Rickie Fowler described completing 36 holes around PGA National without a single bogey as a "big accomplishment" after he set the early clubhouse target at eight under at the Honda Classic.
Fowler matched his opening four-birdie 66 to hit the front on eight under, while good friend and playing partner Sergio Garcia is just two behind after a battling 69 over the Champions Course.
World No 5 Fowler parred his first six holes before getting a putt to drop for birdie at the tough 16th, and he did well to scramble a par at the first after a wayward drive left him unable to reach the green in two.
The 27-year-old picked up another shot at the long third and converted an excellent approach to the sixth, and he signed off in grand style as he holed a 22-foot curling putt for a closing birdie at the ninth.
"I'm just happy to go bogey-free, that's a big accomplishment around this golf course," said Fowler, who led by two shots with two to play on his last outing in Phoenix before driving into water at 17 and eventually losing out to Hideki Matsuyama in a play-off.
"Not just one day, but the two back-to-back, and I'm so pleased with how I've managed my game around the golf course. I got a nice break on the first - my 10th - where I was able to salvage par there. Every once in a while you need to get a little lucky.
"It was nice that we were able to take advantage of that, continue to move forward and make some good putts coming in. Something I can take from that, and continue to swing well and make more putts this weekend.
"It's nice to hit fairways, hit greens, especially in places like this where it's very demanding tee-to-green, and also make some birdies there at the end. So definitely pleased with the first two days and looking forward to the weekend."
Fowler played alongside USA Ryder Cup captain Davis Love III over the first two rounds, and he added: "I've always enjoyed getting to play with Davis. He's someone that I've always looked up to, and the way he's played and the career that he's had, so hopefully I earned myself a chance to get to play for him later this year."
Meanwhile, Garcia found the going tougher on day two as he followed his opening 65 with a hard-working 69 to stay in touch with the leader at the halfway stage.
The Spaniard chipped in for birdie at 17 and came within an inch of a hole in one at the 220-yard seventh, although he blotted his card with two bogeys on the front nine.
"I felt like probably played a little bit better yesterday," he said. "It was a little bit tough, but the course is getting tougher every day. It wasn't easy at all, but overall, I felt like it was a solid round. It puts me in a good situation, and we'll see what we can do on the weekend.
"Rickie is playing really, really well, so I'm going to have to play extremely well to keep up with him. We'll see. He's a good friend of mine and we always enjoy playing together. So it's great to be a part of the same group, and we'll see, maybe tomorrow it would be nice if we can do it again but it's always good fun."
And on his near hole in one at the seventh, he added: "When I saw it rolling up the hill I thought it had a great chance and unfortunately it didn't go in. Making two there was already a good thing, but a one would have been amazing.