SAN MATEO — Nate Hui had never before started a baseball game at the high school level.

On Thursday, you never would have known it. For the first time as a starting pitcher, Hui took his home mound in San Mateo as Serra welcomed in Los Gatos for a trip to the CIF NorCal Division I championship game.

This time, Hui, normally the Padres’ closer, simply decided to close out the entire game in one fell swoop. The junior pitched a complete-game shutout in the Division I semifinal, backstopping Serra to a 3-0 win and the Padres’ first-ever trip to a regional championship. They will play at De La Salle today for the title.

“Honestly, I don’t really feel pressure,” Hui said. “I know my team is gonna make plays behind me. I had a couple double plays, couple good plays in the outfield. And I know if I do my job, I throw strikes and execute the pitches when I need to, I know my teammates are gonna back me up, no matter what.”

Though Hui didn’t allow any runs, that wasn’t always a certainty. Los Gatos (25-6) applied pressure in almost every inning and got started right away.

The Wildcats (25-6) put two runners on in the first, two in the second — advanced to scoring position by Hui’s balk — two in the fourth, one in the fifth, one in the sixth and one in the seventh.

Every single time, Hui came through and stranded them all. And on a day where the whipping Peninsula wind made every fly ball a challenge, the Padres played a clean and error-free game in the field to ensure Hui could put the finishing touches on his masterpiece.

“You walk in, you see 290 and 285 (feet),” Serra coach Mat Keplinger said of the short outfield fences. “But then when the wind’s howling like this, it’s a different ball game. You have to run. You have to bunt. You have to execute the small game when it’s like this.”

Serra (28-6) was the beneficiary of some home cooking from Mother Nature in the fourth inning. With one out and Davis Minton at third, Tyler Harrison hit a soaring pop fly to medium depth in right field.

The wind got a hold of the ball, which hung up for an eternity, and dropped it near first base, where Los Gatos was unable to make a play. Minton scored on the play, and the Padres, with the aid of the elements, had already pushed across enough run support for Hui.

“Anything up in the air is definitely a gamble, right?” Keplinger said. “Hold your breath.”

After getting a run on the board, Hui navigated a two-out single by Zach Biller and a walk to Rowen Smith in the fifth, getting Will Temple to pop out to left to end the inning. He did some of his best work down the stretch, facing just one batter over the minimum in his final two innings.

“Attack the zone,” Hui said of his mindset. “They’re a good team, I know, but we have a great defense, so just let them put the ball in play and trust in my teammates. They’re gonna make plays for me, and go make the right pitches when I need to.”