Which undefeated college football teams are on upset alert in Week 6?

There are 20 FBS teams left without a loss heading into college football's Week 6. Some of those teams were expected (Ohio State, Oregon), some are mildly surprising (Ole Miss and Oklahoma) and some are nearly shocking (North Texas, Houston). But which teams will fall from the unbeaten in Week 6? Here's six unbeaten teams on upset alert in Week 6.

Louisville

The 4-0 Cardinals are probably on borrowed time after escaping with a 34-27 win over a Pittsburgh team that held a 17-0 lead in the first quarter and a 27-17 halftime advantage. Meanwhile, Virginia, who is around a touchdown underdog in this game, is fresh off their impressive double-overtime upset win over Florida State. Chandler Morris could have a big game against an iffy Louisville secondary.

Miami

The highest profile game on this list is the Hurricanes travelling to No. 18 Florida State. Miami has taken care of South Florida and Florida in their last two games, but this Seminole team has a much stronger offense than either of those teams. Florida State has put up at least 31 points in each game and Tommy Castellanos could give Miami some trouble with his dual-threat skills.

Iowa State

The Cyclones actually would pull a tiny upset by winning this game, which is measure of how little respect the No. 14 team is getting at 3-1 Cincinnati. With three one-score wins, Iowa State has lived dangerously throughout the season. Despite veteran QB Rocco Becht, ISU is converting on just 20 of 26 red-zone trips (next to worst in the Big 12). On the other hand, Cincinnati is 17-for-17 with 14 touchdowns and dual-threat QB Brendan Sorsby (1,043 yard and 10 TDs passing, 227 yards and 4 TDs rushing) will be a handful for Iowa State.

Texas Tech

Somebody's unbeaten run will end when 4-0 and No. 11 Texas Tech plays 4-0 Houston. Texas Tech QB Behren Morton is on his way back from a troubling neck stringer and concussion. Meanwhile, Houston has been suprisingly good on defense this year, allowing just 13.3 points and 29% third-down conversions. If Conner Weigman keeps getting time to throw, the passer who has picked up more yards in each game this year (270 last week) could burn the Red Raiders.

UNLV

Dan Mullen's Rebels are an often-overlooked unbeaten squad at 4-0. Frankly, they've been lucky, with three one-score wins in their first four games, including an FCS Idaho State team and a miserable UCLA squad. They draw a Wyoming team that's coming off an off week and seemed to discover its ground game against Colorado, with Samuel Tote Harris rushing for 126 yards. A running back named Tote seems like a good pick to lead an upset.

Texas A&M

The Aggies better watch the game film from Mississippi State's epic battle last week against Tennessee. The Bulldogs, in their overtime loss, forced a trio of turnovers, held Tennessee to 5 for 14 on third down, and generally looked every bit of a dangerous opponent. Yes, this game is at A&M, but like some of the teams above, the Aggies are living dangerously. They won a shootout over Notre Dame and then a grinder against Auburn. This one looks more likely to be a shootout, but the Aggies better be prepared for a battle.