RIVERSIDE — Just when it looked like the story on the Flintridge Prep boys' water polo team's season was coming to a close, the Rebels sent in a rewrite.

Down four goals on the road in their CIF Southern Section Division V opener to the Riverside Poly team that ended their 2012 season, the Rebels were on the ropes. They climbed back in it, though, boosted by a third-quarter explosion and nine-goal night from Ethan Vandeventer for an 18-14 victory Wednesday.

Not only was it win-or-go-home, but win-or-goodbye for 10 senior Rebels who will not be back next season. That fact has already given this postseason a different feel than others for Prep.

“It's the feeling that every game is our last game in high school water polo,” said Prep's John Treinen, who finished with a goal, three steals, two field blocks and six assists, “and we really have to do everything in our ability to extend our high school water polo career.”

While there were so many things to credit in the comeback victory, Vandeventer said it all started with Flintridge Prep Coach Dan Hare's speech at halftime.

“'Rarely in life do you get to dictate how the story ends, give me a second half to this story of four years of water polo that you can, win or lose, take yourselves out of the pool and be proud of,'“ said Hare, summarizing his call to action when Prep was down at the break, 10-7. “The blessing and curse of CIF is you can use that as a motivating factor. You lose and it's over, but we live to play another day.”

Flintridge Prep (14-11) will regroup and play host to second-seeded Los Altos Saturday at noon Saturday at Pasadena Poly in the quarterfinals – where the Bears beat the Rebels last year, 17-9.

While Vandeventer had the most goals in the game, the biggest arguably came from Prep's Diego Delgado, who finished with three goals.

With 1:50 to play in the game and Flintridge Prep clinging to a 15-14 advantage, Vandeventer was ejected in a three-player exclusion.

“I wasn't nervous,” Vandeventer said. “I went into that ejection box with a little smile because I knew my team had me. It was a physical game all around and it shows because I was ejected in the fourth, but I have complete faith in this team.”

Said Treinen: “That was even a bigger motivation for us, we needed to finish this game without one of our best players. We took that and we really came out even stronger without him.”

Once things were sorted out by the officials, the Rebels took possession and eight seconds later Treinen fed Delgado in the post for a quick turnaround goal with 1:42 to play.

“I just looked at Diego and he gave me this look that said, 'I'm going to post this kid up and I'm going to score,'“ Treinen recounted. “I just said, 'OK.'“

Riverside Poly (17-12) failed to score on its next two possessions, with Jamie Walker forcing a steal with 1:25 to go, and the Bears' Zach Ritter (four goals) having his shot blocked in the field by Treinen with 55 ticks to go.

Treinen's field block led to a Walker goal off a Sean King assist with 42 seconds to go. Prep was looking to run out the clock, but its ball movement set Walker up with a shot right in front of the goal he could not pass on.

Walker kept pushing and capped the scoring with 19 seconds to go with his third goal of the night.

“Once he was rolled, Vandeventer passed the torch to Jamie Walker. That No. 2, he's instant offense, just add water,” laughed Hare in reference to Walker.

It brought Flintridge Prep all the way back from an 8-4 deficit with 3:45 to play in the first half. The Rebels scored the first two goals of the game, but gave up a 8-2 run from there to put their backs up against the wall.

Before the third quarter could get underway, Walker started the comeback with a goal nine seconds before halftime, off a King pass inside, to bring Prep within 10-7.

Carlo Sivilotti won all four sprints for the Rebels in the game, with two leading to Prep goals to start the first and third quarter. Treinen scored 14 seconds into the third to pull Flintridge Prep within two, 10-8.

After a Riverside Poly offensive foul 23 seconds later, Vandeventer flipped a switch and scored his first goal of the third on a beautiful skip-shot goal 58 ticks into the frame.

The Bears got one back and went up, 11-9, on a Joey Dempsey (six goals) tally before Vandeventer rallied his team to a tie at 11 with 3:05 to go in the third quarter.

First, Vandeventer drew an exclusion within five meters with 4:36 to play, quickly passing the ball out to Treinen, who gave it right back for an open Vandeventer goal. Another man-advantage was earned by Vandeventer with 3:20 to play, but the excluded Riverside Poly player never left the pool. It led to a five-meter shot and goal for Vandeventer to knot things up with 3:05 to play in the quarter.

For the first time since a 2-1 edge with 3:38 to play in the opening quarter, the Rebels took a lead, 12-11, with 1:11 remaining in the third. The goal went to Vandeventer after he freed himself up on a give-and-go with Treinen.

“I know [Vandeventer] steps up, he takes pride in every single shot he takes and he really stepped up big in this game,” Treinen said. “We knew he was on fire so we kept feeding him. He knew when to shoot, when to pass and just played an excellent game, as our whole team did.”

Vandeventer's dream quarter was not over until he gave his team a 13-11 cushion, 35 seconds before the fourth, with a score off a King helper.

A pair of lob cross-cage goals from Riverside Poly's Ritter and Jonah Saenz kept the Bears within a goal, 14-13, with 4:20 to play.

Flintridge Prep goalie Alex Hirsch Marin (three steals, two saves) set up Vandeventer's ninth and final goal with 3:18 to play when he forced a takeaway and then fed Vandeventer down the pool.

“I'm not going for stats, I'm going for the win,” Vandeventer said. “This team is all about having fun, but right now we have to win every game. We have three more to play; it all starts with one, though.”