Two of the biggest surprise teams of the season will meet in the first round of the Class 6A football playoffs when Kennesaw Mountain visits River Ridge at 7:30 p.m. Friday in Woodstock.

River Ridge (9-0), which opened in 2009, clinched the first region championship and first unbeaten regular season in school history Saturday with a 29-21 victory over Cambridge in a Region 7 game.

The Knights’ had one winning record in their first 11 seasons – an 8-2 finish against a non-region schedule in 2011 – and made one playoff appearance (2012, when they finished 5-6). Second-year coach Michael Collins is 12-7 at a school that had won just 30 percent of its games before his arrival.

Kennesaw Mountain has had an even longer wait for a trip to the playoffs, as the Cobb County school will be in the postseason for the first time in its 21-year history.

Kennesaw Mountain played its first 20 seasons in the highest classification in a region that included some of Cobb’s strongest programs – McEachern, Marietta, Hillgrove, North Cobb and Harrison. The Mustangs struggled to find their footing, winning just five of 52 region games over the past 10 seasons.

They got off to a rocky start this year after moving down to 6A, opening the season with four consecutive losses, including losses to Allatoona and Sprayberry in Region 6 play. However, Kennesaw Mountain got things turned around, winning four of its last five games to slip past Pope into fourth place in the nine-team region.

“It means a lot to our program, our school and our community,” Kennesaw Mountain coach Caleb Carmean told the AJC’s Todd Holcomb earlier this week. “This is a program that has been working for 20 years to break through, and it’s great for this group of players and coaches to be the ones to achieve that goal.”

Carmean is a former three-year starting quarterback for the Mustangs who came back to his alma mater as head coach in 2018.

The computer Maxwell Ratings had pegged River Ridge as the seventh-best team in eight-team Region 7 in its preseason projections. Kennesaw Mountain was picked to finish seventh of the nine teams in Region 6.

Here is the schedule for Friday’s first-round games, with a look ahead to the potential matchups for Round 2.

First-round games

R4 #3 Lovejoy at R1 #2 Valdosta

R2 #4 Statesboro at R3 #1 Evans

R6 #3 Sprayberry at R7 #2 Creekview

R8 #4 Winder-Barrow at R5 #1 Carrollton

R7 #3 Cambridge at R6 #2 Kell

R5 #4 Douglas County at R8 #1 Buford

R1 #3 Northside-Warner Robins at R4 #2 Hughes

R3 #4 Grovetown at R2 #1 Glynn Academy

R8 #3 Habersham Central at R5 #2 Rome

R6 #4 Kennesaw Mountain at R7 #1 River Ridge

R2 #3 Brunswick at R3 #2 Alcovy

R4 #4 Tucker at R1 #1 Lee County

R3 #3 Lakeside-Evans at R2 #2 Richmond Hill

R1 #4 Houston County at R4 #1 Westlake

R5 #3 Alexander at R8 #2 Dacula

R7 #4 Johns Creek at R6 #1 Allatoona

Second-round matchups

Lovejoy/Valdosta winner vs. Statesboro/*Evans winner

Sprayberry/Creekview winner vs. Winder-Barrow/*Carrollton winner

Cambridge/Kell winner vs. Douglas County/*Buford winner

Northside-Warner Robins/Hughes winner vs. Grovetown/*Glynn Academy winner

Habersham Central/Rome winner vs. Kennesaw Mountain/*River Ridge winner

Brunswick/Alcovy winner vs. Tucker/*Lee County winner

Lakeside-Evans/Richmond Hill winner vs. Houston County/*Westlake winner

Alexander/Dacula winner vs. Johns Creek/*Allatoona winner

Note: Teams marked with an asterisk are No. 1 seeds and would be the home teams if they advance to the second round. If a No. 1 seed loses, the winner of the game on the left side of the list would be the home team in Round 2.