Barrington's home run count went up to 48 for the season on Saturday.
But a home run by Loyola had the Fillies in an early count many might not have expected.
Ramblers catcher Brooke Kehoe belted a 3-run blast over the left-center field fence to give Loyola a 3-0 lead with two outs in the top of the third inning.
However, the Mid-Suburban League champs answered with 2 homers in the bottom of the inning and another in the seventh as they rallied for an 8-4 victory over the No. 9 Ramblers (13-11).
The top-seeded Fillies (32-1) will face No. 4. Fremd (24-7) in Tuesday's 4:30 p.m. semifinal game of the Class 4A Rolling Meadows sectional.
Barrington sophomore Keenan Dolezal (25-1) threw a 3-hitter with 11 strikeouts.
The Fillies ended up with 5 hits off Loyola ace Jamie Kiefer (11-10), a junior who was coming off a 15-strikeout performance in the regional semifinal against No. 8 Buffalo Grove.
Two of the Fillies' 3 homers were by second baseman Krista Moore and the other was by third baseman Loren Krzysko, who belted the 41st of her career and 17th of the season.
Moore and Krzysko went back-to-back over the fence with two outs in the bottom of the third.
"I just wanted to help put my team up," said Moore, a senior who has 4 homers this spring. "It was like we said 'We aren't ready to go home.' "
Kiefer had struck out seven of the first 10 batters she faced when Moore hit her first blast.
"We had to start hitting the ball," Moore said. "She's a good pitcher and she brought a lot of power on the ball. We needed to start scoring runs."
After Krzysko's homer sailed over the center field fence, the Fillies were down 3-2.
They took the lead for good in the fourth with 2 more runs, taking advantage of a leadoff walk to catcher Raegan Fingerman, whose courtesy runner Jenna Privatsky scored when Morgan Olszewski reached on an outfield error.
Olszewski's pinch runner Kat Panos scored the second run when Erin Ward grounded out. Panos raced from second to third on the play and then was able to scoot home on a throwing error for a 4-3 lead.
"You can't have errors when you are going against a top seed like Barrington and we are No. 9," said Loyola coach Marty Jennings. "You've got to play great. Offensively, I thought we were great with our approach going against a great opponent and great pitcher.
"Unfortunately, defensively we can't give them extra outs. Credit to them. They're a great team and I wish them luck."
The Fillies added 3 more runs in the sixth to expand the lead to 7-3.
They took advantage of 4 walks (Tess Bolger, Moore., Maggie O'Hara and Olszewski) and 1 error.
Fingerman's RBI single to left was their only hit in the inning. Her courtesy runner Privatsky came home on an error.
Loyola got 1 run back in the sixth when Emily Conway led off with a double off the center field fence, took third on a passed ball and scored on a wild pitch.
The Ramblers got runners on second and third with one out, but Dolezal escaped further damage with a 1-2-3 groundout (she threw first to catcher Fingerman but the runner at third held) and then a strikeout.
"When we were down 3-0 we just had to keep our heads in the game," Krzysko said. "We all stepped up and knew what we had to do.
"She (Kiefer) was one of the toughest pitchers we'd face. She had good speed and she moved the ball well. She kept us off balance."
But not off track from winning a 12th straight regional under coach Perry Peterson, whose team is 3 home runs shy of the single-season state record of 51 set by O'Fallon and Antioch.
"The key to any game is you have to score runs to win," Peterson said about the 3-0 deficit. "When we got behind, we knew the offense had to come alive. We're a good hitting team and we got the offense going when we needed to.
"Their pitcher and catcher (Kiefer and Kehoe) are the heart of a team that plays at a high level of competitiveness, like Loyola does is in all sports."
Other than the 3 homers, Barrington's other extra base hit in the game was a triple by senior Sam Rosenfeld to lead off the sixth inning.
During warm-ups, Jennings said Ramblers freshman second baseman and No. 5 hitter Melissa Miller suffered an upper body injury and was unable to play.
"I'm proud of our kids," he added. "We played our best game against the highest-seeded team. Unfortunately, it wasn't enough. That's the game of softball sometimes."