The first day of the NCAA tournament was a Giant Killer thriller, and not just because seven teams, including four double-digit seeds, pulled upsets. Even better, the triumphs came from squads that profiled as successful underdogs, not flukes. So far, teams we picked as “Best Bets” are 1-0 (with Wichita State getting the win), while those who were “Worth a Long Look” are 3-1; “Not Completely Crazy” picks are 0-5 (with Killers outscored by an average margin of 15.8 points); and “Stay Away” teams are 0-3 (average margin: 26 points).

Best of all, if you enjoy bracket carnage -- and if, as we recommended, you made sure to keep an eye on second-round matchups when you chose your pool -- the Davids who won yesterday are well-equipped to keep toppling Goliaths. Our model sees at least one more upset coming on Saturday.

So far, four programs -- Yale, Arkansas-Little Rock, Wichita State and Gonzaga -- are stepping toward Cinderella status. They are all legitimately strong teams: All four rank in KenPom’s top 41 nationally, and now all four are heading into favorable stylistic matchups. Here’s what we know:

In the Midwest Region, No. 11 Gonzaga doesn’t play much like a Killer, but it’s looking like it won’t have to in order to zig through the early rounds of this tournament. The Zags used their inside game to manhandle sixth-seeded Seton Hall, with typically efficient results: Gonzaga shot 46.2 percent (18-for-39) on 2s and limited the Pirates to 19 percent (4-for-21) on 3s, while Domantas Sabonis posted 21 points and 16 rebounds. Now it faces a Utah squad that commits turnovers on 18.1 percent of its possessions (ranking 181th in the NCAA) and turned it over a whopping 20 times against Fresno State.

It may seem a little crazy that you can ride selection committee seeding mistakes all the way to the Sweet 16, but Gonzaga was a 1-point favorite against Seton Hall, and Vegas has made Saturday's matchup against 3-seed Utah a pick 'em. Our model goes even further: With a difference of less than one point between these teams in our basic power ratings, and Utah’s vulnerability, it gives the Zags a 57.5 percent chance to advance. Honestly, wouldn’t it seem just as plausible for Gonzaga to be the Giant and Utah the Killer in this game?

No. 12 seed Arkansas-Little Rock wiped out a 13-point deficit with 3:33 left in regulation against Purdue, forced two overtimes and finally edged the Boilermakers 85-83, and here’s the thing: The Trojans kept setting up Josh Hagins (31 points) to make crazy shots because they kept seizing extra possessions. Little Rock forced twice as many turnovers as it committed, largely because of its 13 steals, and grabbed a higher percentage of missed shots on both ends than its much taller opponent.

That’s Little Rock’s formula: Keep things slow, protect the ball, force turnovers and limit good shots. And now it’s about to run into its stylistic opposite: Iowa State’s cyclonic shooting machine. If Georges Niang & Co. can impose the fast pace they love, they have the cohesion and accuracy to pile up points (120.4 adjusted points per 100 possessions, ranking third nationally). And against Little Rock, which allows a ton of 3-point attempts, we wouldn’t bet against Iowa State’s outside shooting. But we will note the fourth-seeded Cyclones have vulnerabilities that Iona, who was basically a lower-case version of Iowa State, couldn’t exploit: They don’t grab rebounds, and they don’t force turnovers. So the path is there for the Trojans, who took 15 more shots than Purdue, to once again pile up extra possessions. Our model gives them a 17.8 percent chance of following it successfully.

In the South Region, anyone who didn’t yet appreciate No. 11 Wichita State got to see the nation’s top defense (87.9 adjusted points per 100 possessions) in full strangle mode against No. 6 Arizona. We have sung the Shockers’ praises again and again, and they are on the verge of toppling VCU as our model’s all-time favorite team. They force bushels of turnovers while committing hardly any of their own, they hit the boards and they’re willing to mix it up by launching 3s, even though hitting long-range shots has not been an area of strength this season. And they do it all at a thudding pace with a packed-in defense that just deadens opponents' shooting. We shall never have an unkind word for coach Jim Larranaga, and there is no way his Miami Hurricanes are going to turn the ball over 19 times against the Shockers, as Arizona did. But while No. 3 Miami is a highly efficient team that also plays very deliberately and aims to force opponents into bad shots, it is facing a dogfight here. Basically, anyone would be. Our model gives the Shockers a 37.2 percent chance of continuing their Cinderella quest.

In the West Region, No. 12 Yale neutralized Baylor’s rebounding advantage, as we suspected the Bulldogs might. Indeed, they got off to such a quick start against an especially big Bears starting lineup that Baylor was confused to the point of breaking down, and coach Scott Drew wound up playing Rico Gathers, the country’s top offensive rebounder, for just 16 minutes. It’s not likely that Yale’s next opponent will be outcoached so severely. Fourth-seeded Duke spreads the floor, often with four guards playing at the same time, shoots the lights out from long range (38.5 percent on 3s, ranking 26th nationally) and protects the ball (turnovers on just 14.3 percent of possessions, ranking fifth). As a result, the Blue Devils score 119.9 adjusted points per 100 possessions (ranking fourth), and they’re a lot of fun to watch.

But they are vulnerable on defense, particularly on the boards -- in their last three regular-season losses, they allowed opponents to collect an astonishing 55 offensive rebounds. And of course, that’s Yale’s particular strength: The Bulldogs grab 38.9 percent of their own missed shots (ranking seventh).

The history of similar games makes this an even more interesting matchup. We call Duke a Gambling Giant, focused on the perimeter, and Yale a Slow Killer (like Wichita State, though not as strong overall). When members of those families have clashed in past tournaments, Killers have won five of the 11 games. This batch includes some memorable upsets, like Harvard over Cincinnati in 2013 and West Virginia over Duke in 2008. And even when the favorites won, the games were usually close, as with Saint Mary’s vs. Memphis in 2013 and St. Bonaventure vs. Florida State in 2012. There’s plenty of reason to expect Yale to make this game a slog -- and for Blue Devils fans to start sweating.

Thanks to Liz Bouzarth, John Harris and Kevin Hutson of Furman University for research assistance.