Tony Smaldino, a sophomore who began the year on the junior varsity team, was a hero in Tuesday’s CIF North Coast Section Class A playoff opener.

Smaldino, who transferred to Justin-Siena High School after a year at De La Salle-Concord, came up big in the seventh inning of a scoreless game. Tim Steggall scored from third base on Smaldino’s suicide squeeze on a 1-2 pitch with one out and the bases loaded to give Justin-Siena a thrilling and dramatic 1-0 win over eighth-seeded Marin Academy.

“We’ve been fighting all year, and this is what we live for — it’s the playoffs right now. It’s huge,” said Smaldino, the team’s designated hitter, who bats eighth in the order.

The victory moves Justin-Siena (19-4 overall), the tournament’s No. 1 seed and three-time defending champion, into Friday’s semifinal game at Middletown (18-4), the No. 4 seed and the North Central League I North champion, which began the playoffs with an 11-7 win over St. Vincent-Petaluma yesterday. It starts at 3:30 p.m. at Middletown High in Lake County.

Smaldino came up after back-to-back intentional walks to Garrett Roualdes and Daniel Castillo loaded the bases. He bunted back to the pitcher, Adam Lewis, who overthrew his catcher, Nathan Tone, on the play. Steggall slid into home and probably would have beat a good throw.

“I was just happy to put it in play,” said Smaldino. “Once they intentionally walked Daniel Castillo, I knew right here, right now that I’ve got to end this game — no matter what I have to do.”

“That’s a lot of pressure for a sophomore to step up and do that right there,” said Braves’ head coach Allen Rossi, who called for the squeeze. “He’s a little powerhouse and he plays the game hard. I just felt like we were going to get it done. That’s the reason why I called it. It’s a gutsy call, but the bottom line is that I’ve coached a long time and I felt like that was the right call at the right time. We pulled the trigger and it worked out.”

Steggall, the Braves’ clean-up hitter and shortstop, started off the bottom of the seventh by walking, then advancing to second base on a passed ball. He went to third on Jason Lehman’s sacrifice bunt.

Lewis held Justin-Siena, the Marin County Athletic League runner-up, to just three hits while striking out three and getting a pair of double plays from his defense. The Braves got a double from Castillo and singles from Garrett Wright and Pat Mendonca, but left a runner on second base in the third inning and a runner on third in the sixth inning.

“It took us seven innings to beat them,” said Steggall, who will play for the University of Puget Sound in the fall. “But we knew what we had to do. Their pitcher mixed it up. He kept us off balance all day. That’s playoff baseball. Everybody’s going to come to play, and they did today.”

Matt Leonard pitched superbly in relief of Castillo, the Braves’ starter, who went the first five innings, allowing four hits while striking out one and hitting one batter. Leonard, who will pitch for Cal Poly-San Luis Obispo next year, inherited a runner at second base with no out in the sixth inning. He retired the next six batters in a row and struck out five in two innings.

“We played great defense behind Castillo, who’s going on two days rest,” said Steggall. “He pitched a hell of a game and then Matt came in and shut the door and we did what we had to do to get that one run. I don’t know what’s going to stop us. I think we have a great chance. If we can win games like this, play great defense, and get the runs we need, nobody’s going to beat us.”

Leonard has eight innings of eligibility left this week and will start Friday’s game, Rossi said.

“I think Castillo pitched a great game. And Matt did a great job of coming in and shutting the door,” said Rossi.

Castillo got 10 ground ball outs, and Wright (third base), Steggall (shortstop) and Mendonca (second base) all played well defensively in the infield for the Braves, who are trying to win their fourth straight NCS title in a single-elimination format.

“This is a different team,” said Rossi, who guided last year’s team to a 27-0 mark. “This team’s trying to win their own section championship and put their mark here. I don’t think kids really feel the pressure. They’ve had a lot of pressure games this year and they’ve handled themselves very well.”

Marin Academy (13-9), the Bay Counties League-West champion, left two runners on in the second inning, two in the fourth and one in the sixth. Wyatt Hayman had two hits for Marin.

“We didn’t come here to play a good game or to tie or to just go into extra innings. We came here to beat Justin-Siena,” said Marin Academy coach Lloyd Dorris. “Justin-Siena’s got a couple of pitchers that are really tough ... and Justin-Siena plays great baseball. We had a good, fast game and it was a really exciting game. We had a great season and we came in here prepared. We laid our best game out there. We played team baseball — that’s what we’ve been doing all year. That’s what I’ll remember this ’06 squad for — that they’re a complete team.”

Justin-Siena Notes

The game — which drew a large crowd — was carried by KVYN 99.3 FM with sports director Ira C. Smith doing the play-by-play and David Alessio handling the color commentary. ... In today’s other first-round games, Salesian-Richmond (13-10) is at Head-Royce of Oakland (20-4) and Kelseyville (12-7-1) plays at John Swett-Crockett (18-4). Both games are at 4 p.m. The finals will be June 2 or 3 at a place and time still be determined. ... Lewis will pitch at Haverford College in Haverford, Pa., next year.