After three games, Tennessee's defense is in some pretty unusual territory.

Year in, year out, the Vols typically boast one of the nation's best defenses. But halfway through September, the Vols rank 87th nationally against the run and 81st in total defense.

Maybe more troubling, though, is the way Tennessee let a 10-point lead slip through its finger in the final 17 minutes of a 21-20 loss to No. 5 Florida on Saturday night.

"I'm not a betting person, so don't take this the wrong way, but I would have bet my house that there's not anybody who's going to score on us twice in the fourth quarter," UT coach Phillip Fulmer said. "We've got to correct that. We've got to get that back where it's supposed to be."

Where the defense was in 2005 was No. 2 in the nation and tops in the SEC against the run. In 11 games last season, opponents scored just six second-half touchdowns against Tennessee's defense (UAB, Ole Miss, Georgia, South Carolina, Notre Dame and Vanderbilt).

Saturday, the Gators scored two in their final three possessions to erase UT's lead.

Florida closed the gap to 17-14 with an eight-play 72-yard drive that ended when Chris Leak found Dallas Baker for a 4-yard touchdown pass with 1:16 remaining in the third quarter.

Baker and Leak hooked up again to cap a 65-yard drive with a 21-yard touchdown on their next possession.

"It was disappointing, frustrating," senior linebacker Marvin Mitchell said Monday. "As a defense, things are not always going to go your way. At that point in the game, things weren't going our way."

UT's defense spent 10 more minutes on the field than Florida's, but the 66-play total was only six more than they had against Air Force and one more than the Cal game.

Fatigue wasn't a factor, at least for Mitchell.

"We want to play football for 60 minutes," he said. "That's what we need to go out there and get done. Me, myself, I wasn't tired. I was pumped up and ready to go."

Depth, already a concern before the loss of starters Inky Johnson and Justin Harrell to season-ending injuries, is even more important now.

"It's very important," defensive end Xavier Mitchell said. "We push them hard just to get in there. It's a long haul; Coach Fulmer always tells us it's not a sprint it's a marathon.

"We need those guys to come on so we won't be tired in the fourth quarter when we have to play 72 plays. It's very important just for the amount of games we play throughout the season."

UT's plan, Mitchell said, was to be physical and aggressive against Leak. The Vols kept him under pressure and got three sacks.

True freshman quarterback Tim Tebow, though, rushed seven times for 29 yards, none bigger than his 2-yard sneak to preserve Florida's game-winning touchdown drive.

"He's got a little thunder with him," Marvin Mitchell said.

Florida, though, stole Tennessee's thunder with its rushing game.

DeShawn Wynn became the first back to rush for more than 100 yards against the Vols since Cadillac Williams in the 2004 SEC championship game.

Opponents having much success -- especially running the ball -- is anything but the norm.

Since John Chavis became UT's defensive coordinator in 1995, the Vols have held opponents to less than a 100-yard average six times. But a week after giving up 281 rushing yards to Air Force and its tricky flexbone offense, the Gators tallied 121.

Opponents have averaged 155 yards a game on the ground.

"I think we could do a whole lot better," Xavier Mitchell said. "We pride ourselves on stopping the run, Coach Chavis as well, he drills it into our head. He holds it dear to us. We're going to look forward doing better each and every week."

Marshall enters Saturday's 4 p.m. kickoff (TV: Pay-per-view) averaging 172 yards a game on the ground. It's not exactly West Virginia's 348-yard per game juggernaut, but a mobile quarterback in Bernard Morris and tailback Ahmad Bradshaw will be a nice test.

And a welcome chance to right the ship.