DARTMOUTH — Justin Lopes was playing in his career 12th playoff game on Tuesday night.

He made sure he’ll get a 13th.

The senior and four-year starter snagged three steals in the final two minutes to lift second-seeded Bishop Stang to a 55-48 win over No. 15 Plymouth South in the first round of the Div. 3 South Tournament in John C. O’Brien gymnasium.

“We couldn’t lose,” said Lopes, who scored a game-high 19 points to go with six rebounds, three assists, four steals and a block. “We can’t go out now. It’s how we’ve been since freshman year.”

With two minutes left, the Spartans were clinging to a 47-46 lead over a Panthers team with just three wins on the season and one senior on its roster. Lopes intercepted a pass on the wing and, while he missed the layup, Eric Camacho came in behind him to put back the miss for a three-point lead with 1:50 to play.

A minute later, after senior Dame Perry drove through traffic for a layup to put the Spartans up five, Lopes stole the ball in almost exactly the same place on the floor and, this time, finished the layup for a seven-point lead. After a couple of free throws for the Panthers, Lopes stole the ball one more time and passed the ball up for a Perry layup that clinched the win with 19 seconds to play.

“The defense won it for us at the end, and that’s what we hang our hat on,” said coach Colbey Santos. “That was (Justin) just saying it wasn’t over. He’s a tough kid. He’s done it over and over again. He just refused to lose today.”

The past two years, when the Spartans went cold from deep, they got sent packing, falling to Norwell and Burke. On Tuesday, Stang hit just 2-of-16 3-pointers through three quarters — they finished the game 4-of-20 — but held a seven-point lead thanks to a tenacious defense that held the Panthers to 13 total points in the middle two quarters.

“That’s what it’s all about,” said Lopes of his team’s defense. “We preach havoc. It’s what we preach and it’s what we do. Today, it was all about the defense because our shots weren’t falling. It wasn’t the prettiest game, but a win is a win at this point.”

Everything turned for the Spartans at halftime, after a rough first half that saw them fall behind 10-2 in the opening five minutes and trail 18-8 with six minutes to play.

“We played a little tight,” Santos said. “That’s what this environment does to you. It’s the tournament. You never know what’s going to happen.”

Thanks to strong play on the glass by Collin Johnson, who had five points in the second quarter, Stang finished the half on a 12-4 run and went into the break down 22-20.

“It was coach’s speech,” Lopes said. “He said ‘Seniors, this could be your last game. I know you don’t want to go out like this.’”

The Spartans came out of halftime like a thoroughbred out of the gates, scoring the first 13 points and holding Plymouth South scoreless until Matt Mahoney drilled a 3-pointer with 1:37 left in the third quarter. That ended a 25-4 run for the Spartans, but it also kicked off a hot stretch for the Panthers from deep, as they hit four 3-pointers in the next four minutes. Freshman Matt Cassidy’s 3-pointer with 3:45 tied the game at 43-all.

From there, Lopes and Perry scored 10 of Stang’s final 12 points as the two seniors, inextricably linked over the past four years, ensured they’ll play at least one more game together.

WHAT IT MEANS: The Spartans advance to take on No. 10 Martha’s Vineyard (12-9) at 5 p.m. on Friday. The Vineyarders beat No. 7 Case 63-53 on Tuesday. The Spartans beat the Vineyard 80-59 on Feb. 18 in the Kuliga Classic. “We just have to be more relaxed on offense,” Santos said. “We wanted to swing for the fences and win the game in the first three minutes and you don’t win games like that. It’s a marathon. Each possession matters and offensively, we have to do a better job.”

COUNTING ON COLLIN: The 6-foot-5 Johnson, a freshman, hadn’t played in three weeks, but he needed no time to re-acclimate, scoring seven points and grabbing a team-high 11 rebounds, four of which came on the offensive end. “He came in and helped big-time,” Lopes said. “Rebounds, finishing layups, tough defense. He’s a tough kid. He’s the last one out of the gym every single day, even when he’s hurt. That kid works hard.”

HIGH-FLYING: During the game, Perry literally jumped over a dude. Plymouth South had a player cherry-picking and threw a long outlet pass to him under the basket. As Perry came in for the block, he shot-faked, and Perry like Hamidou Diallo clearing Shaq in the dunk contest. Plymouth South was called for a travel on the play.

STANG STAT SHEET: Perry finished with 16 points, two rebounds, four assists and an emphatic block just before the half. Eric Camacho finished with six rebounds, two assists and a block and Joseph Silvia had four steals. “He goes overlooked a lot,” Santos said. “He just competes and finds a way to steal the ball and gets our tempo going. He was big with his ball presure. That was huge.”

STANG TEAM STATS: The Spartans shot 41.2 percent from the field (21-for-51), 20 percent from deep (4-for-20) and 42.9 percent from the line (3-for-7) while turning the ball over 10 times, although just twice in the second half.

PLYMOUTH SOUTH STATS: The Panthers got 11 points from sophomore big man Hunter Dean, with eight of those coming in the first half. Keven Paul had 10 and Matt Mahoney added nine. The Panthers shot 42.5 percent from the field (17-for-40), 31.8 percent from deep (7-for-22) and 50 percent at the line (7-for-14) while turning the ball over 14 times.

NOTES: All of Plymouth South’s points were scored by underclassmen, with 32 of its 48 points coming from sophomores and a freshman. … Stang scored as many points in the fourth quarter as it did in the first half. … Plymouth South didn’t hit a 2-point field goal in the third quarter. ... Stang beat Plymouth South 73-60 in the first round of the 2018 Div. 3 South Tournament.