One day after Cody Aquino and Randy Castillo combined on a four-hitter, 'Aiea received another fine pitching performance in the semifinals of the O'ahu Interscholastic Association baseball playoffs yesterday.

Derek Grace fired a four-hitter, and Aquino scored on an error in the fourth inning as 'Aiea defeated Kaiser, 1-0, at Central O'ahu Regional Park.

'Aiea — seeking its first OIA championship since 2004 — will play Moanalua for the OIA crown tomorrow at 5:30 p.m. at Central O'ahu Regional Park. The game will be televised live on OC-16.

On Wednesday, 'Aiea shut down Kalani, 7-1, behind Aquino and Castillo. Yesterday, it was Grace's turn.

"Derek Grace pitched an outstanding ballgame," 'Aiea coach Ryan Kato said. "I didn't think Cody's performance could be topped, but I gotta admit, this one-upped him. ... He kept us in the ballgame until we were able to score that one run, and then he just dominated. It was nice to sit back and watch something like that."

Grace, a senior right-hander, walked one and struck out six. He faced just 26 batters in seven innings, and earned his first complete-game victory in four starts this season.

"I really wanted to finish the game because throughout the season, I've never had a complete game," said Grace, who featured a fastball and slider yesterday.

Grace worked out of trouble in the top of the first inning. Leadoff hitter Andrew Uehara singled, and moved to third on Scott Uehara's sacrifice bunt and a wild pitch. Colby Ho walked, but Grace got a flyout and groundout to end the inning.

"I had a hard time locating my offspeed pitch," Grace said. "But our defense made some plays."

Grace had "plenty of pop on his ball," 'Aiea catcher Tripper Chung said. "This is probably the best game I've seen him pitch this year."

'Aiea scored an unearned run off Kaiser starter Russel Sasaki in the fourth. Aquino singled and stole second. After a flyout, Aquino moved to third on a groundout, and scored when Kaiser's shortstop mishandled Reid Nakamura's grounder.

"It was a tough game," Kaiser coach Peter Ho said. "We actually gave them that one run. We had a shot earlier, but we didn't throw him out. We didn't make a basic play. But that's baseball."

In the sixth inning, Kaiser missed another scoring opportunity. Maeda singled with two outs, and was replaced by courtesy runner Michael Kawashima, who stole second. However, Grace struck out the next batter.

Sasaki pitched a five-hit complete game. He struck out one, and was bolstered by two double plays.

Kato said he's undecided on whether to start Aquino or Grace for tomorrow's championship.

"It's still a toss up," Kato said.

Kaiser will play Kailua tomorrow for third place at 2 p.m. at Central O'ahu Regional Park.

KAISER (10-2) 000 000 0—0 4 1

'AIEA (11-1) 000 100 X—1 5 0

Russel Sasaki and Jarryd Maeda. Derek Grace and Tripper Chung. W—Grace. L—Sasaki.

Leading hitter: 'Aiea—Cody Aquino 2-3.

Reach Brandon Masuoka at bmasuoka@honoluluadvertiser.com.