Zillman, the top seed, will play No. 3-seeded Teague Hamilton of Laguna Beach in the championship match Friday at 11 a.m. He's trying for his first title at the tournament also known as the War by the Shore.
"I feel pretty good," Zillman said. "I'm the No. 1 seed, so I didn't do anything that special [yet]. It makes me feel like I have to win a little bit. It's more pressure."
Zillman, a left-handed player, felt the pressure Thursday after easily winning the first set. Masciorini came back and won the second set by the same 6-1 score, so Zillman shifted strategies a bit.
As the third set began he started going more to a looping shot with plenty of topspin. Masciorini tried to flatten those shots out, but often he would miss into the net.
"I just thought I should try to win by not missing anymore, and letting him miss," Zillman explained.
Masciorini called for the umpire serving at 3-4 in the final set, after Zillman called a close ball on the baseline out. But two points later Masciorini dropped his serve, allowing Zillman to serve for the match.
Zillman, who will be a sophomore at Costa Mesa High and is ranked No. 42 in Southern California boys' 16s, did not play high school tennis last year for the Mustangs. He said he might do so in the future.
He's come close before in the War by the Shore. Last year, he was the No. 2 seed in boys' 16s but lost in the semifinals.
Now, he's just one win away.
If he wins, expect another yell.
Corona del Mar High incoming junior Alec Adamson fell in a boys' 18s semifinal Thursday to Ryo Shimizu of Irvine, 7-6, 6-3.
Adamson said he was ahead 4-1 in the first set but No. 4-seeded Shimizu, who plays for powerhouse University High, came back strong.
"He started playing a little better and I was missing some shots," said Adamson, who was unseeded. "It kind of went downhill from there."
Adamson has also been having a strong summer. He has won 18s singles titles at tournaments in Anaheim Hills, Ventura and Beverly Hills.