VALLEY GLEN — The night before the biggest match of his high school career, Corona del Mar High senior tennis player Zach Williams couldn't sleep.

It wasn't because he was nervous. It was because had a very raspy throat and felt nauseous.

Players on CdM sometimes call Williams "Sausage" because of his tall, thin frame. For breakfast on Tuesday, Williams did not eat sausage. Instead, he said he swallowed eight Advil.

"Probably not good for me, but I toughed it out," Williams said.

Williams was not the only one. "Tough" was probably a good adjective for the Sea Kings, who put together a huge team performance when they needed it the most.

Every starter won at least one set as No. 2-seeded Corona del Mar topped No. 3 Harvard-Westlake, 12-6, in a CIF Southern Section Division 1 semifinal match at Los Angeles Valley College. The Sea Kings advance to the finals for the first time since 2003.

Corona del Mar will play University in the Division 1 title match May 30 at The Claremont Club. The Trojans beat Palos Verdes, 13-5. Uni, seeking its third straight CIF Division 1 title, swept CdM in the Pacific Coast League this season, 13-5 and 12-6.

The Sea Kings, who had lost on the road at Harvard-Westlake, 10-8, in last year's quarterfinals, move on this year because of a balanced effort.

"Last year was a team loss," CdM Coach Brian Ricker said. "Every single person lost a set that they thought they could have won. This year was a team win. I think everybody won a set that they could have lost."

The Sea Kings (21-3) started strong and finished strong against the Wolverines (20-3), taking five of six sets in both the first round and third round. They also got a big performance at No. 1 singles from junior Alec Adamson, who swept his Harvard-Westlake opponents Jackson Frons (7-6), Jeffrey Bu (6-4) and Michael Genender (6-3).

"I beat some good players," Adamson said. "I knew it was going to be tough. I wanted to really rise to the occasion, because I knew it was going to be a close match and I really wanted my team to do well. Getting to the finals is really cool."

It was Ricker's first win in four trips to Los Angeles Valley College with CdM's boys and girls over the last two years. Last year, CdM lost to Harvard-Westlake in the quarterfinals at the same venue.

The Sea Kings appeared determined not to let it happen again in Tuesday's first round. They got close doubles wins from all three of their teams. CdM's Alex Murray and Chaz Downing outlasted Adam Williams and Jamie West, 7-5. Williams and Daniel Anastos got past Jaird Meyer and Harrison Kalt, 6-4, and Andrew Nguyen and Paul Kacik topped Max Rothman and Dylan Eisner by the same score.

Throw in Adamson's tiebreaker victory over Frons and Carson Williams' win over Genender (who retired down 5-3), and CdM was already halfway to victory. It surprised Harvard-Westlake Coach Chris Simpson, who saw all three of his doubles teams lose leads.

"I knew they were going to be competitive," Simpson said. "CdM, we respect their doubles teams. But, you know, we should be closing them out. We're at home. To not get any of them, that was a bit concerning, then to lose a tiebreaker too. For any top program, that's not a start that you want."

Simpson's team responded by taking four sets in the second round to pull within 7-5. But the Sea Kings closed strong, particularly No. 2 singles player Henry Gordon and Carson Williams.

The freshman Gordon topped Frons, 6-1, and the sophomore Williams bested Bu by the same score. Soon, the Sea Kings' top two doubles teams also had won and CdM had clinched the match.

"It was all about focusing," Zach Williams said. "We were all like, 'Don't look at other people's matches. Focus on your own.'"

It did not come without some tense moments. Before the third round, Zach Williams said he was having problems breathing. With Williams and Anastos up, 5-1, CdM desperately needed to close out that last set.

"Zach said to me, 'You better not make me serve,'" Anastos said. "He said he would have passed out, which is probably true. I noticed after one of the points, he was like [gasping for air], like he had just gotten the wind knocked out of him."

Before the match Ricker had reminded Zach Williams that Michael Jordan played some of his best basketball games when he was sick. Williams said feeling ill perhaps did help him focus.

Besides Adamson's sweep, it was hard to single out any one player or doubles team. Carson Williams won a pair of singles sets for CdM, coming back strong from a tiebreaker loss to Frons in the second round to beat Bu. Each doubles team also took two of three sets.

Ricker gave credit to Harvard-Westlake for coming back strong in that second round, but also to his own players for finishing the match so well. The Sea Kings finally proved they could win at Los Angeles Valley College.

They drove away in a bus, leaving the Wolverines in need of some Advil.

matthew.szabo@latimes.com

Twitter: @mjszabo