One player can make or break a team's season --- especially if he's on the opposing side. Which players will cause the biggest headaches for each team in Mark Schlabach's post-spring Top 25?
1. Ohio State
Running back Saquon Barkley is the second of two Heisman hopefuls the Buckeyes will face this season (Oklahoma's Baker Mayfield is the other). With a divisional title possibly hanging in the balance, the stakes will be higher for stopping Barkley, who has an uncanny ability to make a play no matter how well a defense is positioned to stop him. There's no scheme that can stop this kind of jump cut. -- Dan Murphy
2. Florida State
Do we have to pick just one pass-rusher as FSU's looming nightmare? There's little question the biggest concern for the Seminoles this year is the offensive line, and the slew of pass-rushers lined up to take advantage is a long one -- from the crews at Alabama and Clemson to rising stars like NC State's Bradley Chubb, Wake Forest's Duke Ejiofor, BC's Harold Landry and Miami's Joe Jackson. In all, Florida State will play 12 players who recorded at least five sacks last season. -- David M. Hale
3. Alabama
If Jalen Hurts and the Alabama offense are going to take a step forward in terms of the passing game, they'll have to prove it right away against safety Derwin James and Florida State in the season opener. Expect James, who can play any position on defense, to roam the field and try to bait Hurts into mistakes. -- Alex Scarborough
4. USC
The Trojans will enter rivalry week already having played 11 games in 11 weeks and, if they haven't already, hope to be in position to qualify for the Pac-12 title game with a win over UCLA. It's still largely assumed that UCLA quarterback Josh Rosen will enter the NFL draft following this season, which leaves him this final opportunity to beat USC. -- Kyle Bonagura
5. Penn State
Penn State's road to defending the Big Ten title this year goes through Columbus, where Ohio State defensive end Tyquan Lewis presents a pretty serious speed bump. The Nittany Lions have improved on the offensive line in the past couple years, but Lewis (eight sacks in 2016) has been a pass-rushing terror. What makes him even more dangerous are the talented teammates who make it hard to figure out who to double-team. -- Murphy
6. Oklahoma State
The Cowboys held Pitt receiver and All-America return specialist Quadree Henderson in check last year in Stillwater. And it's a good thing for Oklahoma State, because even a decent game by Henderson's standard may have turned that shootout in favor of the Panthers, who lost 45-38. It won't be easy to limit him again as the Pokes head to Pittsburgh in Week 3. He returned three kickoffs and a punt for scores last season and led the nation in combined kick-return yardage. Henderson's 2,083 all-purpose yards ranked second in a single season in Pitt history to Tony Dorsett in his 1976 Heisman season, and Henderson was the first consensus All-American as a Pitt sophomore since Larry Fitzgerald in 2003. -- Mitch Sherman
7. Clemson
A year ago, Louisville quarterback Lamar Jackson racked up 457 yards and three touchdowns, but he came up just short of knocking off the eventual national champs in Death Valley. This year, Jackson will be looking for some revenge on his home turf, and the Week 3 matchup figures to be one of the marquee events of the season in the ACC. Clemson's defense is good, but can the Tigers keep Jackson from another Heisman-level performance this year? -- Hale
8. Oklahoma
Led by left tackle Orlando Brown, the Sooners might boast the best offensive line in the country. But that prowess will be put to the test in Week 2 in Columbus. Headlined by end Tyquan Lewis, Ohio State might be even better up front defensively, underscored by a convincing effort in Norman last season. -- Jake Trotter
9. Washington
When healthy, Oregon's Royce Freeman is as dangerous a running back as there is in college football. That version of him was missing for most of the 2016 season as Washington ended a 12-game losing streak against Oregon and made a run to the Pac-12 title and College Football Playoff. -- Bonagura
10. Auburn
Derrius Guice went for 62 yards on just three carries the last time LSU faced Auburn. But this time around there won't be Leonard Fournette to contend with. Guice, who has all the tools to be one of the best running backs in the nation, will test an Auburn defense now without star front-seven players Carl Lawson and Montravius Adams. -- Scarborough
11. Wisconsin
Michigan's Rashan Gary is expected to be well into his breakout sophomore season by the time he travels to Madison in late November for the Badgers' toughest game of the season. The country's former No. 1 overall recruit has the size and athleticism to single-handedly disrupt an opponent's running game, and he can also throw off a quarterback with the help of Michigan's aggressive, blitzing defense. -- Murphy
12. LSU
Like Dak Prescott before him, Mississippi State quarterback Nick Fitzgerald is a lot to handle. In fact, if you ask some on State's coaching staff, Fitzgerald might even be a better runner than his predecessor. You saw it last season when he led the SEC in total offense. If he can become a slightly more polished passer, he could be a nightmare for opposing defenses. -- Scarborough
13. Georgia
Count me as someone else who thinks Mississippi State's Nick Fitzgerald will have a big year. The Bulldogs return a stout defense, but Fitzgerald's ability to be a north-south, east-west runner could give this unit fits all day. He went on a tear with his legs last year, rushing for more than 100 yards in six of the last seven games. -- Edward Aschoff
14. Michigan
J.T. Barrett has scored eight touchdowns in his three previous games against the rival Wolverines. He ran for more than 100 yards and passed for more than 100 yards in each of the last two games. If coach Jim Harbaugh is going to keep from dropping to 0-3 against Ohio State to start his career, it starts with figuring out how to contain the Buckeyes' veteran quarterback. -- Murphy
15. Miami
Considering Miami plays Florida State in Week 3, it is a near certainty that the Hurricanes already are preparing for the Seminoles and quarterback Deondre Francois. In their game last year, Francois took one hit after another but kept getting up, throwing two touchdown passes in the win. Miami returns its entire front seven, so trying to neutralize Francois again must be an integral part of the game plan.-- Andrea Adelson
16. Stanford
In a way, Stanford is somewhat responsible for the emergence of USC QB Sam Darnold. Had its defense not been so effective in slowing down USC a year ago, maybe the Trojans don't make the switch from Max Browne to Darnold. This year, though, the Cardinal heads to Los Angeles in Week 2 where Darnold, the expected No. 1 overall pick in the 2018 draft, will be waiting. --Bonagura
17. Louisville
November is a long way off, and the Cards have to contend with both Florida State and Clemson before then. But Kentucky quarterback Stephen Johnson might be the player nobody in Louisville wants to see again after he accounted for a career-high 421 yards and three touchdowns in Kentucky's surprising win a year ago. Johnson set career marks for passing yards (338) and rushing yards (83), and it's safe to say the Cards will want to avoid another performance like that.-- Adelson
18. Kansas State
Amazingly, K-State coach Bill Snyder never defeated former assistant Bob Stoops in Manhattan. He'll get his chance against Stoops' successor, new Oklahoma coach Lincoln Riley, in what figures to be a key showdown in Manhattan. However, the Wildcats will have to figure out an answer for quarterback Baker Mayfield, who completed 25 of 31 passes for four touchdowns in a rout of K-State last season. -- Trotter
19. USF
This is the year the Bulls face Houston out of the American's West Division, so that means they have to contend with defensive end Ed Oliver, a freshman All-American who proved to be unstoppable at times last season. Oliver led the conference with 23 tackles for loss (No. 2 nationally) and must be accounted for at all times, especially for a team with mobile quarterback Quinton Flowers returning. For proof, look at what Oliver did to Lamar Jackson last season.-- Adelson
20. West Virginia
Oklahoma remains the only conference opponent the Mountaineers haven't defeated since joining the Big 12. The biggest reason? An OU rushing attack that has produced more than 300 yards on the ground in three out of the past four meetings. Corralling new Sooner workhorse back Rodney Anderson will be paramount if the Mountaineers are to finally break through against the two-time defending league champs. -- Trotter
21. Florida
Leonard Fournette is gone, but in his place will be uber-explosive and super-shifty Derrius Guice, who is a more elusive home run threat for LSU. Guice will enter the season as arguably the SEC's most dynamic running back, while Florida's front seven has a rebuilt new look. -- Aschoff
22. Virginia Tech
Let's give a co-award to Clemson's dynamic duo of defensive tackles, Christian Wilkins and Dexter Lawrence. Arguably the best set of interior linemen in the nation, Wilkins and Lawrence present an especially big obstacle for the Hokies, who will need to protect a young quarterback in the pocket and who struggled mightily to run the ball between the tackles a year ago, averaging just 2.64 yards per non-QB run, the worst rate in the Power 5. -- Hale
23. Texas
You can take your pick in Week 3 as the Longhorns head to Hollywood, though quarterback Sam Darnold likely rates atop the list of USC worries for Texas. The 6-foot-4 sophomore is poised beyond his years, according to the Trojans' official biographical data. Unofficially, he's a nightmare matchup for a first-year defensive coaching staff that inherits a talented secondary -- but a group that allowed 258.5 yards per game last year to rank 105th nationally. The Horns surrendered no fewer than 222 yards through the air a year ago in each of their first 10 games. Darnold threw for 3,086 yards as a freshman at USC. -- Sherman
24. Boise State
Washington State quarterback Luke Falk put the NFL on hold for a final year on the Palouse, where he has thrown for 10,888 yards and 89 touchdowns in two-plus seasons as the Cougars' starter. In a loss in Boise last year, Falk threw for 480 yards and four touchdowns (on 71 attempts). -- Bonagura
25. Washington State
The Cougars entered the Apple Cup in Pullman needing a win against the Huskies to secure the Pac-12, but by the end of the first quarter Washington led 28-3 and quarterback Jake Browning had already thrown three touchdown passes. Browning, the reigning Pac-12 Offensive Player of the Year, is 2-0 against Wazzu, and neither game has been close. -- Bonagura