The No. 3-seed Buckeyes led by as many as 14 in the first half, but the 14th-seeded Pioneers came out looking confident and shooting hot in the second.
Sacred Heart got as close as 46-44 thanks to a hook shot by Katlin Sowinski with 12:50 to go, but Buckeye senior Ashlee Trebilcock finally struck a blow for the favorites by draining a three-pointer from the right wing, in front of her bench and a throng of vocal OSU backers.
Then teammate Maria Moeller found herself alone in the right corner and buried another from beyond the arc to give the Buckeyes an eight-point lead, and they began to finally pull away.
Up to the point Trebilcock – yet to play on the winning side in an NCAA tournament game in her college career – hit her big shot, a feeling of, "Here we go again," was starting to creep into an arena full of fans clad mostly in scarlet and gray.
Most surely knew the Buckeyes (28-5) had been dumped out of the tournament by double-digit seeds in the first round the previous two seasons and could be forgiven for wondering if the potential for a three-peat was growing in front of their eyes.
Trebilcock admitted to such a feeling herself, if only slightly.
"When they started making a run, I was never worried that we were going to lose, but I was just like, ‘Oh man. Come on guys! It's right there. We can do it,'" she said.
But where previous incarnations of head coach Jim Foster's Buckeye team might have folded in the heat of a mad March contest, this one responded by outscoring the opponent 22-8 over a second-half stretch of 7:27 to put the game out of reach.
The Buckeyes fly into the second round Monday night for a matchup with No. 11 seed Mississippi State. Tip is set for 7 p.m. back at Nationwide Arena.
"I still think we have a different team," Trebilcock said. "We can withstand runs. We have big-time players that can make things happen, but just for a quick second it was like, ‘Oh man, they're within five. Let's go!'"
That duo also pitched in a combined five assists in the spurt, making opportunities for each other, Trebilcock and Moeller, an unlikely hero who canned the trey that represented the final points in the run as well. That was her fourth successful three-point attempt of the contest and third of the decisive seven-and-a-half-minute span.
For the game, Prahalis led the Buckeyes in scoring with a career-high 23 points, but Foster preferred to point out her 7-to-1 turnover ratio as the freshman pushed her team out of the shadows of tournament failings past, all of which came before she arrived in Ohio's capital city last summer.
Perhaps that was why she did not share in anyone else's concerns.
"I wasn't worried," she said. "They're a good team. We knew they weren't going to go away."
"She took advantage of what opportunities were there for her," Foster said. "In the open floor, you pick your poison, as far as I'm concerned. She's got the ability to go to the basket. She's a great decision maker, and with a couple of those long passes to Jantel loosened her up and got her back in the offense in the second half."
Lavender added 19 points and 10 rebounds, but her scoring came more difficult than usual. She made just 7 of 19 shots from the floor and added 5 of 8 free throws.
"Personally, I think my offense wasn't flowing today," Lavender said. "My teammates stepped up today, especially Sammy. I think we started playing together and we grinded it out."
Trebilcock, who was sitting out a transfer year in 2006 when the Buckeyes last won an NCAA tournament game, finished with 13 points and Moeller had 12, all on three-pointers.
Callan Taylor led the Pioneers (25-8) with 24 points while Alisa Apo added 14.
Sacred Heart, the champions of the Northeast Conference, had a 21-game winning streak snapped but played with the confidence of a team that had not lost since the calendar moved from 2008 to '09.
"My team competed today and that's all I asked of them," said Sacred Heart head coach Ed Swanson. "They went out there, tried, executed the game plan. They played free. They had fun. They played with passion. They played with purpose. Our whole administration, the community back in Fairfield, Conn., we couldn't be more proud of them."
Foster credited the Pioneers for their play, brushing aside the idea his team was nervous at any point.
"I just think we played a good basketball team," Foster said. "I don't think it's anything more than that."
The Pioneers came out scrappy and aggressive, playing the Buckeyes to a draw for the first eight minutes before eventually falling behind when Ohio State made its first big run midway through the first half.
Prahalis was the catalyst for that spurt, too, a 12-2 run that let the Buckeyes turn a two-point deficit into a 10-point lead that would be 12 at the break.
Through 20 minutes, Prahalis led all scorers with 14 points. She also had a pair of assists and two steals while committing no turnovers.
Taylor, meanwhile, kept her team in the game with 13 of her own.