Corinth (29-3) fought back from a 13-point third-quarter deficit against Aberdeen (27-3), then rallied from a four-point hole in the fourth to take a 67-59 win.
In the nightcap, Booneville (25-7) beat another oversized team in Marshall, 60-54, staving off a late rally that saw a 16-point lead dwindle to two.
The rivals, 15 miles apart, will meet for the fourth time tonight at 7 p.m. in front of rabid opposing fan bases. Corinth has won the previous three meetings by 12, 2 and 15 points.
"These kids are just amazing," Booneville coach Michael Smith said. "They're not the most talented kids around, not the best-looking athletes. They've just got heart.
"If Corinth doesn't get up for Booneville and Booneville doesn't get up for Corinth, you're not going to get up."
Corinth made its last state appearance two seasons ago and is trying for its sixth title in 19 trips. Booneville's last trip came in 2000.
After Tamarico Wilson hit two free throws to pull Marshall within 56-54, Marshall rebounded a Booneville miss and with a chance to tie the game, Blue Devils senior Tre Welch stole a pass that led to a Keldrick Lesley free throw with 18.6 seconds to play.
Marshall missed a tying 3 and Lesley sealed the win with two more free throws.
Lesley had 19 points. Marquis Vance had 20 for Marshall (23-7).
"They've had a chip on their shoulder and I can't tell you how much they've grown up in this tournament," Smith said.
In the opener, Corinth saw its deficit go to 40-27 after four straight points from Aberdeen's Fred Ward in the third quarter.
An 18-5 run though ended when Steven Polk tied the game at 45 with 26.9 ticks left in the third.
"We told them when (Aberdeen) got their biggest lead, 'We will make our run. They made theirs. We will make ours,'" Corinth coach Keith Greene said.
Then after Earnest Williams' fourth-quarter slam put Aberdeen ahead 49-45, Corinth made its final run, a run that ended Aberdeen's season with its first loss since Dec. 17, a streak of 23 victories.
Eric Richardson tied the game at 49. Deonta Herman took advantage of an offensive rebound with a 3-pointer and the Warriors went on an 11-2 run that ended with Herman's slam.
"They were just sticking us," Greene said. "We had some shots that were there, just didn't go in. We finally got a couple to go and Deonta rose up and played huge."
The Jackson State signee had only eight first-half points but went for 20 in the second half to lead the game in scoring. Deione Weeks had 12 for Corinth.
Ward had 18, Jakeese Walker 15 and Williams 12 for Aberdeen.
Aberdeen coach Roy Hazzle may have coached his final game after 24 seasons. For the second year in a row, Hazzle suggested in the preseason that he might retire.