Julia Cross estimates that she’s hit millions of balls with Sienna Lynn, her teammate on the Corona del Mar High girls’ tennis team.

That might be only a slight exaggeration.

Lynn keeps track of their practice sets in the Notes app on her phone.

“We’ve played like 30 sets against each other in the past year and a half,” Lynn said. “I’m losing … It keeps me motivated. Something to strive for.”

Cross, a junior, won the Sunset League singles title on Tuesday at Newport Harbor High, beating the sophomore Lynn 6-2, 6-4 in the championship match. It was a clean sweep for the Sea Kings, as Olivia Lew and Brynn Patterson topped teammates Ruby Jacobs and Soraya Burwell 7-5, 6-3 for the doubles title.

All nine Sea Kings starters made at least the semifinals of the league tournament. The six finalists each booked a spot into the CIF Southern Section Individuals tournament, which begins on Nov. 23.

Cross and Lynn teamed to win the league doubles title last year, advancing to the Individuals quarterfinals. This year, they found themselves across the net from each other with the league title on the line.

“I think the whole time, I was trying to play for myself,” Cross said. “I don’t want to lose to her. But in the end, I realized that I’m also playing for my team, playing for CdM, as we both are. We’re going to go to CIF playoffs, and we should be able to forget about this … We’re so close. It shouldn’t be, but I think between us, inside it’s a little bit of a heated rivalry.”

The doubles title went to Lew and Patterson, a pair of sophomores, who topped the sophomore Jacobs and freshman Burwell.

“It was more fun than it was competitive, honestly,” Lew said. “We don’t get to play them in practice a lot. It was light-hearted.”

Patterson was particularly satisfied, as she said she and then-partner Madi Jackson had three match points against Cross and Lynn in last year’s league doubles semifinals, only to end up losing.

Fountain Valley senior Kacie Lam and junior Gwen Nguyen finished third in the league in doubles. After losing 6-0, 6-3 to Jacobs and Burwell in the semifinals, they rebounded to top CdM’s Talia Lubavin and Rachel Carlin 8-0 in a pro set for third place.

Lam said it was her third year in a row in the league doubles semifinals, with a different partner each time.

“Even though it wasn’t the outcome we wanted, I think we left our heart on the court,” she said, adding that she will cherish her memories of high school tennis. “Definitely the best part is the team members itself. It definitely teaches you a lot of life lessons, like how to be patient and how to be a team member. I think this is a huge part of my life.”

Fountain Valley, which finished tied for fourth place in the league, is waiting to see if it will earn an at-large berth into the CIF team playoffs. Brackets will be released Saturday at 11 a.m. — Halloween, as Nguyen noted.

“That could be the biggest scare of the year,” Nguyen said. “A perfect day for it. I said that in our group chat, and nobody replied to me. At least I got a chuckle.”

CdM senior Gigi French finished third in the Sunset League in singles, topping Los Alamitos senior Rhea Udani in the third place match.

Udani, who lives in Seal Beach, and the Griffins will vie in the team playoffs as they tied for second place. Individually, she’s had a great career as a four-year varsity player for Los Alamitos, including three years as the No. 1 player.

This was the first time she advanced to the semifinals of the league tournament, earning a big win over Newport Harbor standout Coco Hine in the quarterfinals on Monday.

“I didn’t play the best today, but I still think that making it this far is nice for my senior year,” Udani said. “The memories are really the matches that I really stayed in, and also [being] with my friends. They’re very supportive on the team, and I think that dynamic of all of us supporting each other, cheering each other on, that’s one of my favorite memories that I really like about being on varsity.”

League champion Corona del Mar (15-1), the defending CIF Southern Section Open Division champion, appears headed back to the top division for the playoffs. The Sea Kings lost six starters from last year, but have grown considerably over the course of the season.

“Our doubles has gotten better, and I think we’ve gotten more hungry in general,” Cross said. “It kind of lives in our heads that we lost that match [that we could have won. Our doubles just didn’t play their strongest that day … but I think we’ve all gotten super comfortable with each other.”