Believe it or not, Week 4 of the high school football season marks the midpoint of the regular season for high school football teams in Classes A and B who play eight-game schedules.

For Class C, which plays a ninth game, that same midpoint is fast approaching – and talk of postseason posturing is on the rise.

Brewer Witches (1-2) vs. Mount Desert Island Trojans (3-0), 7 p.m. Friday at Bar Harbor: MDI matched its 2005 win total last weekend, using strong defensive play led by Wes Chipman and Danny Dunn to shut out Hampden Academy 19-0. The undefeated Trojans also got a balanced offensive effort featuring running back Jon Hall and quarterback Sean Parady.

As it attempts to move closer to its first postseason berth since 1998, MDI must be careful against a Brewer team looking to bounce back from back-to-back losses to two other undefeated PTC Class B teams, Waterville and Gardiner.

Brewer’s lone win so far this season came in its opener against Morse of Bath, which bounced back from its 0-2 start last weekend with a victory over Leavitt of Turner Center – a win that demonstrates the potential balance in the middle of the conference pack.

Bangor Rams (3-0) vs. Cony Rams (0-3), 7 p.m. Friday at Augusta: Bangor treks to the Capitol City for the first of two straight road games, with a date at Messalonskee of Oakland looming in Week 5 before coach Mark Hackett’s club returns home for a potential showdown game against Lawrence of Fairfield on Oct. 6.

The Rams’ fast start has not been without challenges, including last week when they fought off Brunswick 21-14 behind strong play along the line of scrimmage and the third straight 100-plus-yard rushing performance by junior tailback Shane Walton.

Bangor is averaging 37.0 points per game, far more than Cony, which scored its first points of the season last week in a 40-12 loss to Mt. Blue of Farmington. Like Bangor, the Augusta-based Rams have had a challenging early schedule, with opponents Edward Little of Auburn, Brunswick and Mt. Blue all at .500 or better.

Lewiston Blue Devils (2-1) vs. Lawrence Bulldogs (3-0), 7 p.m. Friday at Fairfield: Lewiston’s explosive offense meets Lawrence’s rugged defense in the Pine Tree Conference Class A game of the week.

Lewiston owns wins over Mt. Blue of Farmington (14-7) and Skowhegan (54-26) since losing to Bangor 42-35 in Week 1. The Blue Devils are led by senior tailback-safety Jared Turcotte, who has rushed for more than 500 yards and scored nine touchdowns so far this fall.

Lawrence counters with a rugged defense that already has produced two shutouts this season and has yielded just one touchdown in victories over Skowhegan, Edward Little of Auburn and Oxford Hills of South Paris. The Bulldogs also feature a solid offense led by quarterback Jack Hersom and tailback Aaron Champagne.

When these teams met a year ago, Turcotte was sidelined by a knee injury as Lawrence cruised to a 26-0 victory.

Rockland Tigers (2-1) vs. John Bapst Crusaders (2-1), 7 p.m. Saturday, Cameron Stadium, Bangor: Rockland is seeking its third straight victory since an opening-night loss at undefeated Foxcroft Academy. The Tigers complemented their explosive offense with a strong defensive effort last week in posting their first shutout of the season, a 36-0 victory over Orono.

Junior quarterback Andrew Weiss amassed 205 total yards while tailback Mike Marsh’s playing time was limited by a nagging injury, and freshman Sam Weiss – Andrew’s brother – had a big night with a touchdown run on offense and a quarterback sack in the end zone for a safety on defense.

John Bapst is coming off a rugged week in which it played two games in five nights. The Crusaders gained a split, bouncing back from a 26-8 loss to Bucksport in the completion of a suspended game to earn a 27-13 road win at Maine Central Institute of Pittsfield on Friday night. In that latter game, quarterback Charlie Merritt passed for one touchdown and ran 1 yard for the game-winning touchdown in the fourth quarter.

Marsh rushed for 201 yards a year ago as Rockland defeated John Bapst 49-23.