Old Orchard Beach’s Kaitlyn Cole looks for an opening as Winthrop’s Aaliyah WilsonFalcone defends during their Class C preliminary-round game Tuesday. (Ben McCanna/Portland Press Herald)

OLD ORCHARD BEACH — When the Class C South pairings were announced, Dean Plante knew his third-ranked Old Orchard Beach girls’ basketball team was in for a tough preliminary round game with 14th-ranked Winthrop.

And he was right. The Seagulls led by only one point entering the fourth quarter Tuesday night before pulling away for a 50-38 victory over the Ramblers. OOB held Winthrop to just two points in the fourth quarter.

Going against the Seagulls 1-3-1 zone, the Ramblers hit just 1-of-13 shots in the fourth quarter, had three others blocked by OOB’s 6-foot-2 sophomore center Maggie Strohm and committed four turnovers.

“We played very good defense and that’s a big part of our team,” said Kaitlyn Cote, a senior guard for OOB. “That’s what makes us great, our defense.”

The Seagulls (16-3) will play in the Class C South quarterfinals at 2:30 p.m. Tuesday against No. 6 Richmond. Winthrop, which has just two seniors on its roster, finished 7-12.

“They’ve got a nice team,” said Plante. “They’re young and I think that was to our advantage. Our seniors really played well. They played big-time in big moments.”

The Seagulls had early control of this one, but the Ramblers came back quickly in the second quarter when they hit five 3-pointers. A 3-pointer by Kena Souza gave Winthrop its only lead of the game, 20-19, with 3:29 left in the second. The Seagulls rallied back and led by 31-25 after Brianna Plante (13 points) scored the last five points of the second quarter.

But the Seagulls led only 37-36 entering the fourth.

“It was very nerve-wracking,” said Strohm, who had 13 points and 15 rebounds. “But I knew we’d pull through because we were all positive.”

Winthrop’s first two shots of the fourth went in-and-out, rattling inside the rim before bouncing out. And it never got better.

“That’s been our MO all year,” said Joe Burnham, the coach of the Ramblers. “At times we look like the best-shooting team in Class C. Then it disappears at time. That kind of happen tonight.”

The Seagulls slowly pulled away, keyed by their defense – unlike in the second quarter, when Winthrop’s perimeter shooters were open, the Seagulls got out on every shooter in the fourth. “They made halftime adjustments,” said Burnham. “Credit to Dean and credit to those kids. They were busting their butts and getting out on shooters. But we’re extremely of our kids and how they conducted themselves down here.”

With OOB up 40-36, Megan Niedzwiecki scored off a back-door pass from Brianna Plante. Then Cote scored inside, was fouled, sinking the free throw to make it 45-36 with 4:03 left.

On the Seagulls next possession, Cote hit a 3-pointer from the right wing — about a foot in front of the OOB bench — for a 12-point lead.

“We were like, ‘No, No, No … No way that’s not going in,” said Dean Plante.

“That was so amazing,” said Cote, who had six of her 10 points in the fourth. “It felt so good.”

And not just to her.

“I was so excited,” said Strohm. “I just wanted to jump off my feet. I was so happy.”

Winthrop’s Layne Audet drives around Old Orchard Beach’s Kaitlyn Cole during their Class C preliminary-round game Tuesday. (Ben McCanna/Portland Press Herald)