New putter comes through for Brian Stuard, who’s on top after the first day of the Zurich Classic _lowres

Brian Stuard watches his shot during the 2016 Zurich Classic of New Orleans.

Unheralded Brian Stuard has a simple explanation for his unexpected leap from No. 513 in the world golf rankings to his spot atop the leaderboard Thursday in the first round of the Zurich Classic of New Orleans at TPC Louisiana in Avondale.

“A new putter,” Stuard said after he weathered a 4-hour, 53-minute rain delay and carded a bogey-free 8-under-par 64.

He had birdies at Nos. 1, 2, 4, 7, 9, 10, 13 and 16 en route to his lowest round on the PGA Tour this season, bettering a final-round 65 in the Sanderson Farms Championship, one of his three made cuts in six events.

Stuard’s round featured a career-low 21 putts, thanks largely to a new putter he picked up before playing in last week’s Valero Texas Open at TPC San Antonio. Stuard finished tied for 55th there after shooting even-par 288, good for $14,012.

Twice he has finished second on tour — at the OHL Classic at Mayakoba in 2010 and ‘14.

“I was using an Odyssey Versa, and I just picked this one up on the putting green over there on Tuesday,” said Stuard, a 33-year-old Tour graduate who resides in Fort Worth, Texas. “It felt pretty good after just hitting a few putts with it. So it was like, ‘Give it a try,’ and I putted well last week.”

Out with the Odyssey Versa, in with the Odyssey Fang. Hello, red numbers.

And why not? First-round shot statistics were incomplete because play could not be finished Thursday before darkness set in, but it’s safe to say Stuard putted lights out. He made putts totalling 175 feet, 6 inches, including birdies of 33 and 221/2 feet on Nos. 2 and 4 and par saves of 321/2 and 20 feet on Nos. 12 and 17.

“I stuck the old putter in the trunk of my car,” Stuard said as he huddled with his caddie in the parking lot. “This new one might be in the bag for a while.”

Stuard held a one-shot lead on the field as he approached his third shot on the par-5, 576-yard 18th hole. He stood 118 yards from the pin with a 52-degree wedge in his hand when the horn sounded, ending play a minute before high noon.

Stuard said he killed time around the clubhouse “looking at my phone, watching the clock tick and kept checking the radar, and (the rain) didn’t seem to want to go away.”

When play resumed nearly five hours later, Stuard flicked his approach within 19 feet and got down in two for his 10th par.

“I’ve been struggling to start the year,” he said. “But I feel like it’s getting closer. I just need to see some results, and today was a good one.”

Three more efforts like Thursday’s, and Stuard might be at the top of the leaderboard when it counts the most — after Sunday’s round.