KNOXVILLE, Tenn. – The magnitude of the injuries decimating Tennessee's offensive line is perhaps best exemplified by Devante Brooks' improbable emergence as a starter.

Brooks was sidelined by torn anterior cruciate ligaments his last two years of high school and hadn't played a single down for most of his first two seasons with Tennessee's program. That changed last week when depth issues caused the redshirt freshman to make his college debut as the Volunteers' starting right tackle in a 24-10 victory over Southern Mississippi.

"When you look at Devante, it was the first time he'd really played competitively in a game situation since his sophomore year in high school," Tennessee coach Butch Jones said.

Tennessee didn't have many other options.

The Vols entered the season believing they could lean on the strength of their offensive line, but injuries have turned a perceived strength into a weakness. Tennessee needed to sacrifice the redshirt of freshman Riley Locklear last week just to have six available linemen for Southern Mississippi.

"I don't think there's any coach on our staff that's been through it like this," Jones said after the game. "Especially when we started the season, that was the best depth situation we've had here ever. Now we're down to six."

Tennessee (4-5, 0-5 SEC) hopes its line could get some reinforcements before its Saturday game at Missouri (4-5, 1-4). The Tigers have 68 tackles for loss to rank second in the Southeastern Conference and tied for 14th among all Football Bowl Subdivision teams.

Jones says tackles Brett Kendrick and Drew Richmond, who have combined for 15 starts this season, are questionable for the Missouri game after injuries prevented them from playing last week. Tackle Marcus Tatum, who has made three starts this year, will miss a third straight game.

All those injuries caused Tennessee to use a makeshift line last week with Brooks making his college debut at right tackle and redshirt freshman Ryan Johnson making his first career start at right guard. True freshman Trey Smith moved from his customary position at right guard to left tackle, where the former five-star recruit has a bright future. The rest of the line included left guard Jashon Robertson and center Coleman Thomas.

"Just playing the sport of football, especially in the offensive line category, you're banging your body against 300-pound men," Smith said. "You're going to get nicked up or bruised. We have e great mentality on the line. It's the next man up. Guys have stepped in."

Tennessee has started six different combinations on the offensive line. No lineman has started every single game at the same position.

Tackle Chance Hall, who made a combined 13 starts in 2015-16, is redshirting this year due to a knee injury . Guard Venzell Boulware announced in early October he was leaving the program . Guard Jack Jones retired from football two weeks ago due to neck and shoulder injuries.

The impact is apparent from Tennessee's production on offense.

Tennessee is averaging 20.8 points, down from 36.4 last season. The Vols are gaining 3.6 yards per carry, down from 5.2 a year ago. Tennessee has allowed 20 sacks in its last four games.

Part of the reason for the dip is the departure of last season's top playmakers. Quarterback Joshua Dobbs, running back Alvin Kamara and wide receiver Josh Malone all were selected in the first four rounds of the NFL draft. Tennessee lost its top returning receiver when Jauan Jennings suffered a season-ending wrist injury in a Labor Day evening victory over Georgia Tech .

But the injuries on the line certainly haven't helped.

Tennessee's linemen believe they're on the verge of turning the corner. They're proud of the way they've dealt with all the injuries and note their recent progress. After getting held to single-digit point totals in three straight games, Tennessee has averaged 25 points in its last two contests.

"I think we have a bunch of grinders right now," Smith said. "We always have. Whatever it takes to do, we're going to do it."