A 3-pointer at the buzzer gave Maine South a 19-12 lead over Maine West at halftime of Thursday's championship game of the Warriors' own Class 4A regional in Des Plaines.
"I thought that 3-pointer would really hurt us," said Maine West coach Derril Kipp.
Instead, the Warriors came out of intermission on a mission.
With senior Brittany Collins scoring 20 of her game-high 24 points in the final two quarters, the No. 4 Warriors got past the No. 5 Hawks 44-39.
The Warriors defeated Maine South by the same score during the regular season in Park Ridge.
Maine West (17-11) will face top-seeded New Trier in Monday's 6 p.m. semifinal of the Maine East sectional.
It marks the 23rd regional title for the Hall of Fame coach Kipp, who also watched sophomore guard Monica Liwag collect 8 points with 3 assists.
Liwag hit a big 3-pointer which helped ignite the Warriors' comeback early in the second half.
"Monica came in against their zone and she hit a couple of 3-pointers," Kipp said. "She made a big difference in the game."
Also making a difference, as usual, was Collins, whose 3-point play broke a 37-37 tie with 42 seconds left in the game.
After Maine South (21-9) got to within 40-39, Collins added a free throw and Erin Ross (8 points) hit 2 free throws for the final margin of the game.
Maine South missed a 3-pointer in the final seconds and Collins grabbed her 14th rebound, ending the contest.
"Brittany was really unstoppable in the second half," Kipp said. "And she made four shots from outside. She usually doesn't take that many from outside. Abbey Herling did a real good job on defense, too."
Last Friday, Maine East dropped a tough decision at Maine East and finished second in the Central Suburban North.
One week later, the Warriors were first in a regional.
"It's a great feeling after last weekend," Kipp said.