The biggest guarantee of each March Madness is that no No.1 seed will lose in the first round, but it’s almost as much of a lock that at least one No.12 seed will upset a No.5 seed. For some reason, this round of 64 matchups produces upsets year after year.

Only two times in the last 26 years have no No.12 seeds advanced to the Round of 32. In the last two years, six of the eight No.5 seeds lost their first NCAA tournament game. The No.12 seeds that win their first game often advance to the Sweet Sixteen, as nearly 20 of the 44 No.12 seeds to advance beyond the first round have made it to the second weekend.

The 2015 NCAA Tournament could feature a few memorable No.5 vs. No.12 matchups, as all of this year’s No.12 seeds are mid-majors. Below is a look at the betting odds for each contest, and the chance that each underdog has of pulling off an upset.

No.5 West Virginia-4.5 vs. No.12 Buffalo

Buffalo has never played a game in the NCAA Tournament, but that hasn’t affected their perceived chances of advancing to the round of 32. The Bison are the smallest underdogs of all the No.12 seeds, and both teams finished the season at 23-9.

The Mountaineers are ranked No.20 in the AP Top 25 poll, led by head coach Bob Huggins, who usually advances beyond the first round. He and West Virginia were bounced in the first round of their most recent NCAA Tournament appearance, but the coach had gotten at least one victory in 13 of his previous 16 trips to the Big Dance. West Virginia enters the tournament having lost three of their last four games, while Buffalo hasn’t been defeated since Feb. 14.

No.5 Northern Iowa-6 vs. No.12 Wyoming

Northern Iowa has been the best of all the No.5 seeds this season, winning 30 of 33 games and ranking No.11 in the AP Top 25 poll. The Panthers have experience as a team looking to pull off a major upset. In 1990, they were a No.14 seed and topped No.3 Missouri in the first round. Twenty years later, they famously beat No.8 UNLV and No.1 Kansas in the first weekend, as Ali Farokhmanesh hit one of the biggest three-pointers in recent March Madness history.

Wyoming could prove to be a formidable opponent, having picked up multiple wins against tournament teams. They’ve beaten Boise State twice, and the Cowboys defeated San Diego State in the Mountain West Conference championship.

No.5 Utah-6.5. vs. No.12 Stephen F. Austin

Utah has the best championship odds of any No.5 seed, given a 60/1 chance to win the title. But they also might face the biggest challenge of any No.5 seed. Buffalo is the smallest underdog of the No.12 seeds, but Stephen F. Austin might have an even better chance of winning their tournament game, considering they were in the same position last year. As the No.12 seed, they upset No.5 VCU in the first round.

Leading scorers Thomas Walkup and Jacob Parker played for the Lumberjacks a year ago, combining to score 34 points in the upset. They’ve helped Stephen F. Austin win 28 of their last 29 games, but the beginning of the year could be evidence that Utah will be too much for the No.12 seed. From Nov.18-24, the Lumberjacks lost three consecutive games, all to NCAA Tournament teams.

No.5 Arkansas-7.5 vs. No.12 Wofford

Wofford is the biggest underdog of all the No.12 seeds. They've struggled against upper echelon competition, losing to Duke and West Virginia by 62 combined points. The Terriers lost to Stanford by 15 points in the season opener, and the Cardinal have been relegated to playing in the NIT.

But Wofford won’t be a pushover, having lost just one game since Jan. 15. They got a road win against North Carolina State on Dec. 14, and Arkansas lost multiple games to teams that didn’t make the tournament, losing to the likes of Clemson, Tennessee and Florida. Wofford could have a lot of trouble with Bobby Portis, who is averaging 17.5 points and 8.6 rebounds per game.