You know the old saying that's become a cliché by now -- defense wins championships.

Except, in college basketball, it's true with basically no exceptions. In the KenPom era since 2002, every team that has won the national title has been a top-25 squad in defensive efficiency at the end of the tournament. Of course, you must be able to package it together with offense (all but one was a top-20 team in offensive efficiency), but defensive efficiency is a crucial component.

In an unfamiliar arena, shooting can go cold. Free throws are a box of dynamite. Generally, teams with better defense are more consistent night-to-night because D is less reliant on conversion.

Which five teams in this year's NCAA Tournament have defenses that stand above the rest?

5. San Diego State Aztecs

Realistically, this article should be more about teams like the San Diego State Aztecs, who can steal multiple games in the tournament on the strength of their defense.

San Diego State was a bit unlucky to get a 5 seed, but don't go penciling in the 12-5 upset right away. The Aztecs sit 10th in KenPom's defensive efficiency ratings and 5th in BartTorvik's. Combined with their slow pace (252nd in adjusted tempo, per KenPom), they'll likely drag any team into deep waters.

They posted 11 separate games allowing 60 points or fewer, including holding a fellow Mountain West tournament team, Boise State, to an average of 59.0 points per game in two meetings.

Before you count out SDSU based on their strength of schedule, they actually played the 15th-toughest schedule for a defense in KenPom's metrics. They're battle-tested entering this matchup with a College of Charleston squad that's relied on pace (29th in adjusted tempo) to score rather than their half-court offense.

4. Houston Cougars

If you want to talk about the top seed that'll just put opponents in the meat grinder, that's the Houston Cougars more than any of the other three.

Out of 363 Division I teams, Houston ranked 343rd in adjusted tempo this season. That's likely why you see Houston among the nation's leaders in avoiding the large scoring runs against them.

Along with a reduced level of AAC competition, their tempo and defense have led to some pretty hilarious box scores this year. They've held 11 teams to fewer than 50 points for the game.

Now, guard Marcus Sasser is one of the best players in college basketball and a tremendous perimeter defender, and Sasser's absence due to a groin injury was likely a factor in their 75-65 loss in the conference title games against Memphis. That was the second-most points they've allowed in a game all season.

Sasser might have the chance to rest up against Northern Kentucky before a more stiff test in the Round of 32. If he returns in a modest state, the Cougars are the rightful favorite to win it all.

3. Alabama Crimson Tide

Four of these defenses play at a slow tempo, but the Alabama Crimson Tide are a unique challenge in this tournament.

While they play at the fourth-highest adjusted pace in the nation (per KenPom), they also bring tremendous defensive prowess to the table. They're third in adjusted defensive efficiency at both KenPom and BartTorvik despite the elevated number of possessions.

Nonetheless, 'Bama still posted several dominant defensive outings. They held Auburn, Missouri, Arkansas, Tennessee, and top-seeded Houston to fewer than 70 points in head-to-head matchups.

Some of these other top contenders boast talented offenses, but Alabama was 19th in offensive efficiency and sports arguably the tournament's best player, Brandon Miller. If their off-the-court problems don't interfere with this year's run, Alabama might add a basketball title to their football dynasty.

2. UCLA Bruins

If there's one of these defenses that's proven to show up when it matters most, it's the UCLA Bruins.

There aren't many offenses in the country tougher than Tommy Lloyd's Arizona Wildcats, and UCLA had plenty of chances against them. In three meetings this season, UCLA held them to an average of 64.0 points per game. Behind the nation's ninth-highest adjusted tempo, Arizona scored 82.7 points per contest as a whole, so that's incredibly impressive.

That, plus an offense ranked 25th in offensive efficiency, is what has put UCLA on track for a third straight Sweet 16 appearance as the West Region's two seed. Though they'll have to get through Kansas, Gonzaga, and Connecticut, they've shown an ability to defend high-level offenses before.

UCLA (230th in adjusted tempo) doesn't play as fast as Alabama, but they mirror their efficiency on both ends of the floor. They're BartTorvik's second-best D, and KenPom has them as the top overall defense in the country.

1. Tennessee Volunteers

There's an old adage in basketball that defending is a lot easier when your own shots go in. After all, you avoid transition opportunities that way.

That's why I put the Tennessee Volunteers as the top defense to watch in the tournament. They rank just 49th in both KenPom and BartTorvik's offensive efficiency rankings. Yet, they're the top defense in the country according to BartTorvik, and KenPom has placed them second.

They made this list last year before succumbing to an undervalued Michigan squad that somehow ended up as the 11 seed, but they might reverse that trend with a favorable draw this year. They're comfortably in the easiest overall region.

Considering the tallest player on the floor for them is 6'9" forward Olivier Nkamhoua, they don't have a ton of size, but this is a versatile, switchable defense that would give most teams in the bracket fits. They held five different SEC foes below the 55-point threshold in conference play this year.

However, last year, UM's Hunter Dickinson was a size mismatch at center that the Vols couldn't overcome. They're in the same region as Purdue's Zach Edey, so they'll look to avoid the same fate in 2023, but if they were to somehow clear that hurdle, this is a defense capable of winning it all.