Top-seeded Fredericktown knocked off Notre Dame 55-48 while No. 2 Dexter held on to defeat third-seeded Perryville.
Fredericktown (22-4) and Dexter (19-5) will meet for the district championship tonight at 6:00.
Notre Dame's season ends at 14-12 while Perryville finished 17-8.
The Dexter-Perryville game was a rematch of last year's district championship game.
"We had a motto before the game, just basically coming into the game was 'Let's live 'til tomorrow,'" said Miller. "Find a way to get to tomorrow night and not be satisfied with getting there, but from this point on, boy it's one game at a time. You can't look forward two or three games down the road.
Dexter got some help from Perryville in the fourth quarter as the Lady Pirates shot themselves in the foot from the charity stripe, missing five straight free throws, including three one-and-one situations.
Dexter hit 14-of-18 free throws in the fourth quarter to ice the victory. Dexter's Taylor Nelson had a chance to clinch the game with 11 seconds left and the team up 33-31. She made the first free throw but missed the second, only to see Haylee Finch grab the offensive rebound.
Finch was fouled and sealed the game with two free throws with nine seconds left.
"Who would have thought that someone coming off of a reconstructive knee surgery would be able to get in there and out-jump -- literally, I saw her hands go up higher than anybody else's -- and get a strong rebound?" said Miller of Finch's big rebound.
But one of the true catalysts for the Lady Bearcats was intense defense.
"I thought my girls really played good defense tonight -- they played very aggressive defense," said Miller. "I wasn't upset with all the fouls that we committed because I think it kind of kept them a little bit off-track on what they wanted to do.
"I thought Natalie Hayes played good defense on Amber Hacker. She's their leading scorer. I told (Natalie) before the game, I said, 'I just got a feeling you're going to have a big night.' I thought she played good defense."
Hacker, who scored her 1,000th career point on Tuesday, was limited to nine points Thursday night.
Dexter led 8-2 after the first quarter. But Perryville took control of the game, out-scoring Dexter 12-3 in the second quarter to take a 14-11 halftime lead.
Perryville extended the lead to 21-13 midway through the third quarter, but the Lady Pirates went cold from there.
Dexter went on an 8-1 run to close the quarter, cutting the lead to 22-21.
After a Molly Burleson shot to start the fourth, the Lady Bearcats didn't trail the rest of the game as they took a 23-22 lead. Neither team was able to score another point in the quarter until Finch made 3:36 left in the game to extend the lead to three.
Finch led the Lady Bearcats with 12 points off the bench. She also grabbed numerous key rebounds.
"Haylee has worked as hard as I've ever seen anybody as far as coming off of an injury," said Miller. "When you really look at it, she's only six and a half months past knee surgery. Honestly, coaches are amazed that she's actually even playing. I don't know how much she's going to be able to play tomorrow night, but she's a competitor. I've got a lot of competitors on this team, but Haylee did step up tonight."
Krista Miesner led Perryville with 17 points.
Nelson added 10 points for Dexter.
Now Dexter, ranked 10th in Class 4, will set its sights on No. 5 ranked Fredericktown.
"This is where you want to be," said Miller. "You want to be here on Friday night. Fredericktown is a very worthy opponent. They deserve to be the No. 1 seed. They're a great ballclub. He's got height, he's got size, he's got speed, he's got shooters and he's a good coach. He's been in this position several times before."
In the first game of the night, Fredericktown's inside defensive presence caused numerous problems for the Lady Bulldogs as they swatted away 13 shots in the game.
Fredericktown's 6-foot junior, Betsy Royer, rejected 11 shots.
The Lady Cats jumped out to a 14-11 first quarter lead and extended it to a 26-22 halftime advantage.
Fredericktown pushed the lead to 41-29 heading into the fourth quarter. Notre Dame never got closer than the final margin.
Courtney Kemp, a sophomore guard, led the Lady Cats with 22 points. Amy Hendricks added 12 points.
Notre Dame was led by Kristain Burger's 22 points and Merideth Medlin's 10 points.