Pauline del Rosario fired her best round on the Epson Tour — a sparkling seven-under-par 65 — to surge into contention at the opening round of the Reliance Matrix Championship at Spanish Trail Golf Club in Las Vegas on Thursday.

Just one stroke back is fellow Filipina Clariss Guce, who is chasing a third tour victory.

The 27-year-old Del Rosario, who joined the circuit in 2022, is making her sixth start this season. She has made the cut twice, including a Top 10 finish at the Atlantic Beach Classic last March.

Taking advantage of receptive greens and favorable pin placements, Del Rosario came out firing.

“It shows me that I’m capable of going low out here,” she said. “It gives me the confidence that I have the game to compete at a high level.”

She turned in five-under after a birdie spree on the front nine, then added three more birdies in the first four holes on the back before her lone bogey on the 15th.

Del Rosario is tied for second with American Mariel Galdiano and Thailand’s Cholcheva Wongras, just a stroke behind rookie Carla Bernat Escuder.

Guce, a 10-year veteran, carded a bogey-free round highlighted by an eagle and four birdies.

Two other Filipinas also broke par, with Dottie Ardina shooting a 69 and Bianca Pagdanganan birdieing her final hole to finish with a 70. Samantha Bruce opened with a 72, while Tomita Arejola carded a 74.

Escuder wasted no time making a statement. The 22-year-old Spaniard opened with a blistering start on the back nine, racking up two eagles and two birdies, including an eagle on No. 11 and another on No. 18 to turn at 6-under. She stayed hot with birdies on Nos. 1, 3, 4, and 6, but a double bogey on her final hole denied her a record round, settling for an 8-under 64.

“I think I was very good with the control of my distance and just being disciplined,” Bernat Escuder said. “I knew how far I was hitting my long woods and my hybrid, so that really helped.”

Despite the late stumble, she remained upbeat.

“I just finished like five minutes ago. I think that will really hurt me, but generally I’m hitting the ball well,” she said. “I just need to control those nerves because I put pressure on myself.”

Galdiano, currently No. 4 in the Race for the Card, matched Del Rosario with a 65 highlighted by a 5-under front nine and an eagle on the par-5 11th.

“I’d say ball striking, definitely my irons,” said Galdiano. “I was hitting them close. A little shaky at the end, but I managed to save par on my last two holes.”

Wongras, meanwhile, carded a bogey-free 65 — her best round as a professional on the Epson Tour.