Newport's Nathan Chaness, 2, far left, looks to shoot around a stampede of CdM defenders in the first round of the U.S. Lacrosse Southern Section South Division playoffs on Tuesday. (Don Leach, Daily Pilot / May 6, 2014)

For the second time in four seasons, Corona del Mar High and Newport Harbor opened the U.S. Lacrosse Southern Section South Division playoffs. Each time, CdM Coach G.W. Mix has had a quarrel with having to face the Back Bay rival at the start of the postseason.

Emotions run high whenever the two boys' programs play the annual Battle of the Bay game during the regular season. Jack it up a couple of notches when they meet in the first round of the playoffs.

Keeping those emotions in check proved to be top priority for Mix on Tuesday, when his Sea Kings played host to the Sailors. For the most part, CdM played with composure, allowing it to move on to the next round.

The Sea Kings routed No. 15 Newport Harbor, 12-3, beating their nemesis for the 11th straight time. The pace favored CdM, which produced seven goals in transition and went five for five on man-up chances.

Next for CdM (14-1) is a Thursday home game against No. 10 Tesoro (10-8), which topped No. 7 Beckman, 12-5. The Sea Kings avoided seeing Beckman (15-4), the lone team to beat them this season. Mix preferred to not see the Sailors again.

"Sure it's tough," Mix said of going up against Newport Harbor. "I'm not sure there [are] too many draws that are, you know, a gift. But at the same time were we a little bit surprised that [the playoff selection committee] would give the No. 2 seed a rivalry game in the first round of the playoffs? Sure. It would've been pretty easy to swap the No. 14 [El Toro] and the No. 15 [Newport Harbor], or the No. 16 [Trabuco Hills] and the No. 15 [Newport Harbor], and kind of avoid all of that nonsense, but, you know, it's the second time it's happened in … four years. We dealt with it and our kids dealt with it, but it's just not what you expect being the No. 2."

What Mix counted on was his team getting past the Sailors, just like CdM did in the playoffs three years ago. All evening, CdM, which is trying to reach its fifth U.S. Lacrosse Southern Section South Division final in six years, looked like the faster and fresher side.

The Sailors (8-9) ran out of gas, losing by nine goals at CdM again this season. They went into the second matchup riding a six-game winning streak, having scored a Newport Harbor single-game record 20 goals on Friday.

Four days later, the Sailors finished with a season-low three goals. By the time Newport Harbor managed to score with 2:51 left in the first half, CdM's Ben Palitz had already recorded three goals, and Nino Chavez, Jay Damon and Jack Denning had one apiece.

The Sea Kings jumped out to a 6-0 lead, thanks to Brett Greenlee and Hugh Crance coming up with key steals, giving the team fastbreak opportunities. The first goal came after a turnover, Greenlee (three ground balls), a Denver commit, snatching an errant pass, before racing to the other side to assist on the goal by Chavez 2:11 into the opening period.

John Mooers provided Newport Harbor's first goal, coming on a man-up advantage. He went low on goalie Hoyt Crance, who made four saves. Two minutes into the second half, the Sailors scored again. Kole Escher attacked near the top of the crease, making it a 6-2 game and ensure that he scored in all of the Sailors' 17 games this season, a Newport Harbor record.

The Sailors began to control possession in the third period, as Nathan Chaness won a rare faceoff against CdM's Jason Simaan, who won 12 of 15, and the Sea Kings' bench and players were called for penalties. The Crance twins, along with Brian Leguay, Daniel McCabe, Chad Redfearn and Ryan Brown, slowed the Sailors down.

The rest of the way, CdM outscored Newport Harbor, 6-1, getting a second goal from Chavez, two from Stephen Von Der Ahe and Sherwin Gersten, and another from Noah Howe. Von Der Ahe added an assist and two ground balls, while Howe had two assists and three ground balls.

Escher, a senior, added his second goal three minutes into the fourth period. Alex Fuller's assist, from behind the cage to a wide-open Escher, led to Escher finishing with a Newport Harbor single-season-record 54 goals.

The season didn't end the way Escher and the Sailors wanted. Before CdM eliminated them, Sailors Coach Mark Todd said he and Mix talked about how unfair it was that the two programs squared off so early in the playoffs.

"Yeah, I mean they're a pretty good team for a first-round match, right?" said Palitz, who added two assists and two ground balls. "It's not like the ideal first round you want to have because you know they're going to give it 110%. But then also you know it's not their ideal matchup either, going against a No. 2 seed and going against also their rival."

david.carrillo@latimes.com

Twitter: @DCPenaloza