Week 4 of the college football season basically features three big games:

No. 16 TCU at No. 6 Oklahoma State, No. 17 Mississippi State at No. 11 Georgia, and A Top-10 Upset to Be Named Later.

In that last group, five top-10 teams hit the road as solid but not quite definitive favorites against rising foes, four of which are unbeaten.

Someone’s going to lose. That’s what the odds say. Good luck figuring out whom.

First, the S&P+ projections, which have also picked the rest of the weekend:

Alabama at Vandy: Bama by 20.1 (88 percent win probability)

Michigan at Purdue: Michigan by 17.7 (85 percent)

USC at Cal: USC by 14.8 (80 percent)

Penn State at Iowa: PSU by 14.1 (79 percent)

Washington at Colorado: Washington by 11.6 (75 percent)

(No. 3 Oklahoma heads to Baylor as well, but with the Bears stumbling down an endless flight of stairs and the Sooners a 27.5-point favorite, we’ll ignore this one.)

Each of the five teams has at least a three-in-four chance of winning, and all are comfortable favorites for a reason.

But these odds would tell you that there’s only about a 35 percent chance that all five teams win. Hell, those odds are just a little bit higher than the chances of at least two of these teams losing (24 percent).

I’m far too much of a hedger to pick a STONE COLD LOCK of an upset from this group, but we should prepare for the distinct possibility of at least one CFP-shaking upset.

Let’s take a look at each of the five games and look at the most likely upset path for each of the underdogs. If or when an upset happens, here’s how each is most likely to take place.

Alabama at Vanderbilt

Vanderbilt’s most relevant advantage: passing downs

So far in 2017, the average success rate on passing downs (second-and-8 or more, third-and-5 or more, fourth-and-5 or more) in FBS is 30.5 percent. Alabama hit 33 percent against Colorado State, 25 percent against Fresno State, and only 5 percent against Florida State.

Vanderbilt allowed a 10 percent passing-downs success rate to Middle Tennessee, 11 percent to Alabama A&M, and 15 percent to a ranked Kansas State. The Commodores are allowing a 45 percent completion rate overall and have allowed only one pass of 30-plus yards in three games.

It seems like this could be a big deal, yes? Alabama’s passing game is: Jalen Hurts looks for Calvin Ridley, then takes off running. There is no No. 2 receiver. Whatever the Alabama passing game might become with a crop of exciting freshman wideouts, it hasn’t yet.

How an upset happens

If Vandy can slow down the Alabama run game and keep Hurts (and backup Tua Tagovailoa, who has seen action in each of the last two games) in awkward downs and distances, the Dores should be able to keep this a low-scoring slog.

That’s comfortable territory. In Derek Mason’s three-plus years, VU has played in 16 games in which teams combined for fewer than 40 points. Granted, they’ve only won five of them, but in a slog, you only need a happy bounce or two to pull an upset.

Penn State at Iowa

Iowa’s most relevant advantage: neutralizing the pass rush

In three games, Iowa’s Nathan Stanley has not yet been sacked on a passing down. And after a slow start in the Hawkeyes’ opener against Wyoming, Stanley has completed 17 of 28 passes for 271 yards on such downs.

The Hawkeyes’ run game hasn’t been nearly as good as I anticipated — Akrum Wadley and Nevada transfer James Butler have combined to average just 4.3 yards per carry — but they’ve made up for it with a passing game that has been a step ahead of expectation.

Though Penn State’s defense has been mostly dominant against Akron, Pitt, and Georgia State — 13th in passing downs success rate, second in passing downs explosiveness (IsoPPP) — the pass rush has been only average. There’s no immediate reason to expect that to change in Iowa City.

How an upset happens

The biggest change for Penn State in 2017 is that the hunter has become the hunted. The Nittany Lions have to play on the road against four pretty good teams — Iowa, Ohio State, Michigan State, and Maryland — that they beat on the way to the Big Ten title last year.

For Iowa to get revenge, it will require extreme ball control. The Nittany Lions have shown almost no weaknesses thus far, but Iowa is easily the sturdiest opponent yet. If the Hawkeyes can avoid negative plays and convert third-and-7s, they can keep the explosive PSU offense off the field, define the terms of the game, and give themselves a clear shot at a late win in front of America’s favorite home crowd.

USC at Cal

Cal’s most relevant advantage: Big plays

That USC has had to survive a couple of early scares might not be a bad thing long-term. The Trojans waited until the fourth quarter to pull away against WMU, and Texas took them to overtime in the Coliseum last week, and while part of this was due to bad bounces — they have suffered an incredible 7.6 points per game of bad turnovers luck thus far — they have also had to deal with glitches.

USC has given up 14 gains of 20-plus yards (88th in FBS) and ranks 94th in IsoPPP and 114th in rushing IsoPPP.

Cal has made 15 plays of 20-plus yards (41st) and ranks 35th in IsoPPP and 33rd in rushing IsoPPP. The Golden Bears have forced even more turnovers (nine) than the Trojans have committed (six).

How an upset happens

If glitches remain an issue for the Trojans, Cal appears more than capable of taking advantage. Golden Bear running backs Patrick Laird (7.5 yards per carry in 2017) and Vic Enwere (5.8 against Ole Miss last week) could find some open-field opportunities.

Take those rushes to the house, mix in a happy turnover margin, and you’ve got yourself one hell of an upset opportunity.

Washington at Colorado

Colorado’s most relevant advantage: Standard-downs efficiency

If your only impression of Washington this year is that lackluster, 30-16 win over Rutgers, you probably got the impression of a team that was still fine defensively but might be suffering a 2016 hangover on offense.

Since then, it’s been the opposite. The Huskies outscored Montana and Fresno State by a combined 111-23, gaining 926 yards in just 123 snaps; they rank sixth overall in success rate and 13th in IsoPPP.

Their defense, however, has been a little too bend-don’t-break. The Husky defense ranks just 81st in standard-downs success rate and 47th in passing success rate. They’re closing out drives when they get the chance, but they’re taking their sweet time creating those chances.

Colorado’s offense isn’t in fifth gear yet, but Steven Montez is completing 68 percent of his passes, and the Buffs rank 37th in passing success rate. In wins over Texas State and Northern Colorado, he completed 30 of 37 standard downs passes for 426 yards.

How an upset happens

If UW’s defense remains reactive, that could offer Montez and the Buffs an opportunity to get a step ahead in the play-calling department. They’ll have to create a little room for running back Phillip Lindsay — something they couldn’t do in last season’s 41-10 loss to UW in the Pac-12 title game — but the passing game will be they key to ball control and a CU win.

Oh yeah, and CU will have to finish drives in the end zone. That’s been an issue for both the Buffs (112th in finishing drives) and Husky opponents (13th).

Michigan at Purdue

Purdue’s most relevant advantage: Forcing passing downs

For what is an otherwise excellent team, Michigan has been incomprehensibly bad on first down this year.

Michigan has snapped the ball 88 times on first down. The Wolverines are averaging a not-completely-awful 5.3 yards per play, but of their 464 total yards gained, 211 have come on five plays. They have gained one yard or fewer 43 times. Success rate: 33 percent — 27 percent rushing and a much healthier 46 percent passing. It gets even worse when the Wolverines generate scoring chances. Yards per play on first downs in the red zone: 1.1. They’ve gained zero or fewer yards in eight of 12 instances.

Michigan’s offense currently ranks 114th in standard-downs success rate. Purdue’s defense: 13th.

Finding yourself in constant second-and-9s or third-and-8s, in front of a Ross-Ade Stadium with more energy than it’s had in years, sounds like a less-than-perfect proposition.

How an upset happens

When Purdue has the ball, you’ll be watching one of the more intriguing tactical battles of the year.

Michigan’s defense, led by Don Brown, is spectacular at disguising its intentions and sending five-star athletes at flat-footed opponents.

Meanwhile, Purdue head coach Jeff Brohm has quickly proved that the same things that worked so brilliantly at WKU can work in West Lafayette.

The game will probably be decided, however, when Michigan has the ball. If Purdue is able to at least stay neutral in field position (Michigan three-and-outs would help a lot) and hold the Wolverines to field goals when scoring opportunities arise, the Boilermakers could be in this until the end.