ALGONA — The momentum here Friday night with a spot in the Class 3A state semifinals on the line swung in the direction of Mount Vernon just before halftime.

The Mustangs picked off a pass to keep Algona out of the end zone and hold their deficit at 22-7.

From there, four second-half Bulldog turnovers led to a heartbreaking 31-28 victory for Mount Vernon, which advances to the UNI-Dome for a semifinal matchup with Humboldt at 7 p.m.

The other semi matchup pits Dubuque Wahlert against Sergeant Bluff-Luton at 4 p.m. in Cedar Falls.

Algona (9-2 overall) did everything right for the first 23 minutes of play, as Nathan Manske hit Evan Allie and Tate Slagle for touchdown tosses while running in another. Slagle, who has committed to the University of Iowa to play baseball, also booted a 29-yard field goal.

Following a key flag on the defense that led to a Jase Jaspers short TD run for Mount Vernon, the shift in momentum started coming. The Mustangs picked off Manske — the first interception of the season for an Algona quarterback.

Mount Vernon (11-1) came out of the break and marched right down the field, as junior Kellen Haverback hit classmate Michael Ryan on a 33-yard scoring strike. Following a Bulldog fumble, Bennett Harp kicked through a 24-yard field goal to make it 22-17.

Another Manske turnover led to a 29-yard touchdown pass from Haverback to Cooper Hird, giving the Mustangs their first lead of the game.

Haverback threw for 190 yards while Ryan had six catches for 104. Hird, the leading rusher for Mount Vernon, carried the ball 23 times for 112 yards.

Algona would answer right back after the three turnovers, as Manske hit Slagle on a perfect play for an 85-yard TD. Slagle, who stopped just before the end zone to force the defender to miss him, then carried a Mustang defender into the end zone.

On the very next series, though, Mount Vernon saw Haverback and Ryan hook up once more, this time from seven yards out followed by a successful conversion between the two again.

The Mustang defense forced a turnover on downs by Algona and were able to run the clock nearly out before punting it away. A last-ditch effort by the Bulldogs came up empty, sending off a celebration by the Mount Vernon faithful who made the 186-mile trek northwest.

Manske threw for 286 yards on 17-for-33 passing. Slagle caught seven balls for 172 yards, and Allie had six for 78. William Weichert ran for 60 yards.

Algona’s defense recorded four sacks, as Landon Thompson had two. Taevyn Zinnel and Iowa State University commit Jack Limbaugh added one each.

Ezra Oldenkamp had a fumble recovery, and Allie recorded an interception.

Injured all-state quarterback Alex Manske, a three-time all-stater, had Tommy John surgery in Texas earlier Friday to repair a tear he suffered earlier this year at Humboldt. Since the 2019 season, a Manske has played quarterback for Algona for every down between Alex, older brother Tyler, and now Nathan — a sophomore.

Coming into Friday night, the trio had thrown for 10,085 yards with 108 touchdowns while rushing for 2,627 yards and 42 more scores while winning 39 games.

This marked the final contest for Algona seniors Alex Manske, Limbaugh, Slagle, Blake Grandgenett, Cadyn Samp, Ashton Moreno, Thompson, Oldenkamp, Owen Johnson, Elijah Wilhite, Drew Schutjer, Aiden Ulrich, Ryan Weier and Tysen Wickman.