The Gordon Lee Lady Trojans led by 10 after one quarter, but had to stave off a four-quarter rally by the No. 6-seeded LaFayette Lady Ramblers for a 37-32 victory that sent them to the semifinals.
Canaan Burnett had 10 points and Sarah Meadows eight in the win. Shayla Ludy scored 10 of her game-high 16 points in the fourth quarter for LaFayette.
Gordon Lee will move on to face No. 2 Ringgold in a 7 p.m. semifinal game on Friday.
In boys' action, No. 3 Heritage found itself down 35-31 to start the fourth quarter, but outscored No. 6 Rossville 17-7 over the final seven minutes to pull out a 48-42 victory.
Cole Wilcox paced the Generals with 14 points. Seth Carter and Corbee Wilson had 10 each, while Tylon Gaines added nine.
Grayson Moore had 17 for the Bulldogs, 11 in the third quarter, while Jacob Gadd hit three three-pointers and finished with 11 points.
Heritage will take on No. 2 Trion in the final semifinal game on Friday night.
Thursday's games will pit the No. 4 Dade County girls against No. 5 Lakeview at 4:30. The winner will face top-seeded Heritage Friday at 4:30 in a semifinal game.
At 5:45, the No. 4 LaFayette Ramblers will do battle with No. 5 Dade County with the winner drawing No. 1 Gordon Lee in a 5:45 semifinal on Friday.
The girls' championship game will tip off at 12 noon on Saturday with the boys' game to follow.