SANTA ANA — Much of the talk in high school boys' water polo over the past week has been about the CIF Southern Section Division 1 seedings.

Coaches have made cases for being No. 2 or No. 3. A big reason that's important is that nobody wants to face No. 1 Mater Dei until they absolutely have to.

The Monarchs again showed why they are the team to beat in Division 1 in their home pool on Saturday night. They came out very strong and cruised by Newport Harbor, 15-4, in the regular-season finale for both schools.

The Division 1 brackets will be released at 9 a.m. Sunday. Both Mater Dei Coach Chris Segesman and Newport Harbor Coach Robert Lynn said Saturday night that they expect Newport and CdM to occupy the No. 4 and 5 spots, in some order, in Division 1.

That would mean the Back Bay teams could potentially meet in the quarterfinals. Unfortunately for the Sailors and Sea Kings, that would also mean the winner would most likely face Mater Dei in the semifinals at Irvine's Woollett Aquatics Center.

Mater Dei (27-0) is obviously going to be very tough to beat. The Monarchs, the two-time defending Division 1 champions who have won a Southern Section-record 75 straight matches, were dominant on their senior night. They opened up a 5-0 lead after the first quarter. Junior Kent Inoue scored all five of the goals, one of them coming on a penalty shot.

It was not the start Lynn wanted to see from the Sunset League champion Sailors (20-6). The first time they played Mater Dei, in the finals of the South Coast Tournament, the Sailors were locked in a 4-4 tie deep in the fourth quarter before Mater Dei rallied for a 7-4 victory.

"We got our [behinds] kicked," Lynn said. "[Mater Dei] came out on us fast. We told them it's going to happen if they don't watch themselves. We're disappointed [as coaches], and I'm sure they're disappointed. The game was over before some of the kids woke up. That's how disciplined they are. We've talked about mental discipline the whole year here, and just doing the right thing, being in the right place and the right fundamentals with your legs. Unless you're willing to change it ... the coach can only sit there and talk how long, until the kids are willing to change it. There were a couple of kids that I watched that did not take three strokes hard the whole game, and I'm wondering what's in their brain."

The Sailors hope they didn't lose more than just the game. Senior defender Dan Stevens, a team captain, had to leave the game after he was tangled up with Mater Dei senior center Jon Walters in the second quarter. The scramble happened after Walters' shot went off the crossbar.

Stevens went out holding his left ear. He briefly came back into the game late in the third quarter.

"He wanted to get back into the water, and I said, 'It's up to you,'" Lynn said. "I think he's going to be OK, but he's got to go to the hospital and have it checked. I didn't see anything ruptured, but he said he can't hear out of the left ear."

At the time, the Monarchs were up, 6-2. The USC-bound Walters, a Newport Beach resident who has scored 111 goals this season, started causing more havoc with Stevens out.

He scored twice in the final two minutes of the half, then twice more in the first two minutes of the third quarter. Suddenly, Mater Dei was up, 10-3, and the rout was on.

Inoue led Mater Dei with seven goals, most of those from the perimeter, and Walters had five.

"Kent's a good shooter," Segesman said. "It's tough to read his shot. He has kind of a goofy arm, and a good release. He's comfortable from that four-five position. With Kent, I just think he got hot. Sometimes he's hot or cold, but he's been more consistent of late, and tonight it showed. Hopefully, that continues."

Junior goalie McQuin Baron made nine saves for Mater Dei and backup goalie Carter Yonkers, also a Newport Beach resident, made two saves in the fourth quarter. Other Newport Beach players on Mater Dei's roster include James Walters, Nick Silvers, Jeff O'Brien, Neil LeVecke and Connor Talleur.

"It's a good tuneup as we head into the playoffs," Segesman said. "That's the way we look it at it ... We just have to make sure that we stay focused. That's the biggest thing."

The Sailors, who have scored a season-low four goals in both of their games against Mater Dei, were stymied. They converted none of their seven power-play opportunities, missed one penalty shot off the left post and had another one blocked by Baron.

Senior Curtis Fink led Newport Harbor with two goals and three steals, and he drew four exclusions. Senior co-captains Stevens and Preston Lee also scored for the Sailors, who will need to quickly regroup.

The Division 1 playoffs begin with the first round Wednesday, and quarterfinals on Saturday.

matthew.szabo@latimes.com

Twitter: @mjszabo