LA CAÑADA — Loaded with high expectations, the Flintridge Prep boys’ water polo team, ranked fifth in CIF Southern Section Division V, stumbled a bit out of the gate.

But after Tuesday afternoon, the Rebels believe they’ve righted their ship and are headed on the right course.

Bolstered by a match-high five goals from senior John Treinen and an all-around excellent effort from senior Ethan Vandeventer, Flintridge Prep easily won its home opener, besting Sherman Oaks Notre Dame, 11-5, in nonleague action.

“The main thing was coming out big for our home crowd in our first home game, showing we can win some games and do some damage,” said Treinen, who gave the Rebels a 2-1 lead 24 seconds into the second quarter that they would never relinquish. “We took advantage of our home pool and played our best game.”

Flintridge Prep (6-7) has played a slew of higher-division foes, including South Pasadena (No. 3 in Division III) on Saturday in a 10-7 loss at the Los Altos Tournament, but lost to Division V foe Burbank, 14-7, a week prior when it was without four starters.

With all but one starter back against Notre Dame, though, the Rebels believe they’ve remedied their ills, starting with Saturday’s performance, which, although a loss, was a better showing than a previous 11-6 defeat against South Pasadena.

“Today was the first time we’ve had five of our six starters,” Treinen said. “Today, we definitely turned it around from Burbank. That was the time we knew we had to turn it around.”

After allowing an early goal to Notre Dame (no record available) to fall behind, 1-0, the Rebels turned it around to the tune of five straight goals on the way to a 6-2 halftime lead.

“This is a good one for us. I think this is it,” said Rebels Coach Dan Hare of his team playing to its capabilities. “[I] think we just started doing our thing.

“They had some big guys, so we were really gonna try to take advantage of our team speed and good defense leads to good offense. ... I like the run and gun.”

Leading, 7-3, going into the fourth quarter, Prep put the game away emphatically with a four-goal run off a Treinen score, a Diego Delgado tally off a Vandeventer steal, a Harrison Wagener rebound of a Treinen shot and a Vandeventer tally for an 11-3 advantage with 2:33 remaining in the game.

Vandeventer finished with two goals, three assists and two steals, while Delgado had a goal, two steals and two assists. Carlo Sivilotti also had a pair of goals.

“This is exciting, it’s a team concept,” said Hare, who navigated the Rebels to one of their best seasons in years in 2012, as they took second in the Prep League, earned Division V’s fourth seed and advanced to the CIF quarterfinals. “We’ve got some impressive pieces, but it’s all about playing as a team and everybody knows their role.”