As we hit the second half, it's time to start thinking about what teams need to do to make a playoff run or enter the conference championship mix. For some, it's fixing an issue on defense. For others, it's getting a key player back to health.
Here is the key second-half storyline for each Top 25 team:
No. 1 Alabama
Can someone -- anyone -- challenge the top-ranked Tide? Because with all due respect to the teams that came before, they just haven't done it. Not even Texas A&M, which was ranked the No. 22 team and lost by 22 points. But looking ahead, there might be hope. Maybe not against Tennessee, of course, but the first Saturday in November and a road trip to No. 5 LSU. Then there's a home game against a ranked Mississippi State. And, as always, the Iron Bowl will be a battle. Someone needs to give Alabama a run for its money so it doesn't go into postseason play untested. -- Alex Scarborough
No. 2 Ohio State
The Buckeyes are undefeated thus far, but it hasn't always been pretty. The defense has had its struggles, and coach Urban Meyer has said it needs to be fixed before the end of the season. There have been issues particularly in the secondary, where Ohio State ranks No. 59 in pass yards allowed per game. That is very unusual for an Ohio State defense, and if the team has playoff aspirations, it will need to be addressed at some point. And there won't be any help from star Nick Bosa, who is dealing with an injury and will not return this year, in order to prepare for the NFL draft. -- Tom VanHaaren.
No. 3 Clemson
Though the Tigers have established themselves as one of the best rushing teams in the country behind Travis Etienne, all eyes will once again be on quarterback Trevor Lawrence and the quarterback situation as he gets more comfortable as the starter. Gaining more balance will be key as the Tigers prepare to play some of the more challenging rush defenses on their schedule. Over the next two weeks, they face NC State and Florida State, which rank in the top 15 in the nation in rush D. Right behind quarterback play is watching for more consistency out of Clemson's secondary. Ryan Finley will certainly put them to the test on Saturday. -- Andrea Adelson
No. 4 Notre Dame
The Irish are heavily favored in each of their remaining five games. ESPN's Football Power Index gives Notre Dame a 65.5 percent chance to beat USC in the season finale, and every game before then has considerably better odds. Brian Kelly's biggest task until December will be making sure his team doesn't get ahead of itself or slip up on any given week. A single loss might be enough to end his team's playoff hopes. -- Dan Murphy
No. 5 LSU
Can the Tigers beat Bama? (Same as every other year, right?) After beating No. 2 Georgia and getting off to a 6-1 start, LSU is a legitimate playoff contender. If the Tigers are able to run the table -- which would include a win over the Crimson Tide -- they would be in a great position going into the SEC championship game. Knocking off Alabama is easier said than done, though, as the Tigers haven't done it since 2011. -- Sam Khan Jr.
No. 6 Michigan
Karan Higdon has strung together five consecutive games with at last 100 rushing yards behind an offensive line that has steadily improved throughout the season. Other options, such as fullback Ben Mason and quarterback Shea Patterson, have added to the Wolverines' ground game. If they can sustain that success against good defenses, this team could challenge for a Big Ten title. -- Murphy
No. 7 Texas
The biggest obstacle blocking the Longhorns from a return to prominence this decade has been consistently underwhelming QB play. Yet since a season-opening loss at Maryland, sophomore Sam Ehlinger has consistently delivered for Texas, perhaps the biggest reason why the Longhorns have emerged as a favorite to reach the Big 12 title game. Assuming he overcomes a first-degree sprain to his throwing shoulder during this bye week, Ehlinger -- and whether he can keep the hot hand -- will determine just how far these Longhorns can go. -- Jake Trotter
No. 8 Georgia
How will the Bulldogs bounce back after losing at LSU? And, maybe more important than that, is a quarterback change on the horizon? Coach Kirby Smart doesn't appear to be hitting the panic button. Nor does he appear ready to pull Jake Fromm for Justin Fields. But if you're a team with playoff aspirations and the offense continues to struggle as it did against LSU, a change might be necessary. Fromm is an effective passer and leader, but Fields brings something different to the table with his athleticism. -- Scarborough
No. 9 Oklahoma
OU's defense just hasn't been good enough in recent seasons. That all came to a head after the Sooners gave up a Red River Showdown-record 48 points to Texas in a loss, prompting Lincoln Riley to fire coordinator Mike Stoops the next day. Coming out of a bye week, will the Sooners be any sharper defensively under interim coordinator Ruffin McNeill? The answer to that will decide whether OU can still make a run at the playoff. -- Trotter
No. 10 UCF
Does UCF have a legit shot at the College Football Playoff? That storyline has gained steam in the first half of the season now that the Knights are a top-10 team -- a far different scenario than at this point last season. CFP executive director Bill Hancock has said there is a path to the playoff for the Knights, but not many are buying that right now. Mostly because chaos has to happen. To have any shot, UCF needs to win out and look impressive in doing so (a close win over Memphis did not necessarily help the cause). Shoring up the run defense remains a priority. -- Adelson
No. 11 Florida
The Gators have played well-enough defensively that, once again, their defense should keep them in every game left on the schedule. That front seven, in particular, has made one play after another. But many still aren't sold on Feleipe Franks, who has shown vast improvement over where he was a season ago. Sure, there remain confounding plays, but otherwise, Dan Mullen has done an excellent job calling plays to suit Franks' strengths. But there needs to be more consistency there, especially if Florida has any shot at upsetting rival Georgia next week. -- Adelson
No. 12 Oregon
After several years as the Pac-12 preeminent program, the Ducks fell on hard times over the past few seasons, but following their win against then-No. 7 Washington on Saturday, they're on the brink of a return to prominence. Oregon doesn't need to win the conference to maintain its momentum -- there's a case to be made that it is already ahead of schedule under first-year coach Mario Cristobal -- but the Ducks can't fade out of the race, either. -- Bonagura
No. 13 West Virginia
The Mountaineers have to find out what happened to their so-called high-powered offense in Ames. West Virginia amazingly attempted only 42 plays and gained just 152 yards of offense, as Iowa State completely controlled the game. With Will Grier at QB, the Mountaineers still own the firepower to go toe-to-toe with Big 12 front-runners Texas and Oklahoma. But whether it's better pass protection or more precise execution on third down, the offense will have to make some major adjustments coming off the disappointing showing against the Cyclones. -- Trotter
No. 14 Kentucky
Can the Wildcats' offense do enough on the days Benny Snell Jr. doesn't have it going? The star running back has been the bell cow for Kentucky so far, but when Texas A&M found a way to keep him in check, the Wildcats couldn't generate a consistent offensive attack. When opponents stack the box against them, QB Terry Wilson and the Kentucky pass-catchers have to make them pay. -- Khan Jr.
No. 15 Washington
Will the Huskies let two difficult losses define their season? Unlikely. Even though the Huskies have struggled to generate much momentum this season -- factoring in preseason expectations as a possible playoff team -- coach Chris Petersen's track record is too good to suggest this team will fade out of the conference race. The defense will be fine, but the offense needs to start generating more explosive plays. -- Bonagura
No. 16 NC State
Dave Doeren has one word to explain what NC State needs to do in the second half of the season: finish. Because that is something that has escaped the Wolfpack recently. In particular, NC State needs to finish the job against Clemson after coming close the last two years. The two meet again Saturday as the last two undefeated teams left in the ACC. In all likelihood, this game will determine who plays in the ACC championship game. The Wolfpack finally have their running game going to balance out the passing game, and the defense has been solid. The key to finishing is avoiding the mistakes that have derailed their efforts in recent years. -- Adelson
No. 17 Texas A&M
Will the Aggies get better in the red zone? Against Power 5 competition, Texas A&M is scoring touchdowns only 45 percent of the time (10 touchdowns in 22 red zone trips). That's 50th nationally among the 65 Power 5 squads. The defense is playing at an elite level right now, but they'll have to improve inside the 20 if they're going to continue to win. -- Khan Jr.
No. 18 Penn State
The Nittany Lions have back-to-back losses to Ohio State and Michigan State and are at 4-2 on the season. There are still some big tests ahead, though, and how they finish the season will be the biggest storyline for this team. Can they bounce back and beat Iowa, Michigan and Wisconsin, or will we see them sputter out to finish the season? Not all is lost just yet for this team if it can finish with the two losses it currently has. Whether they can do that, is the biggest question. -- VanHaaren
No. 19 Iowa
For Iowa, sitting at 5-1, the team will be trying to finish out the season strong while also watching what happens with Wisconsin. Both teams now have one conference loss; however, Iowa's loss is to the Badgers. If the Hawkeyes want to make it to the Big Ten championship game, they are going to need some help from Wisconsin's opponents the rest of the way. Both teams still have big tests ahead with Penn State on each team's schedule as well as Northwestern. Iowa needs to take care of business and hope another Big Ten opponent can take down Wisconsin in the process. -- VanHaaren
No. 20 Cincinnati
The Bearcats are off to an incredible 6-0 start and are ranked in the Top 25 for the first time since 2013. That run includes an opening win against UCLA, but the biggest tests are still ahead of Cincinnati. Whether or not the team can get through a gauntlet of Navy, USF and UCF all in a row is yet to be seen. Those three games, especially the test against UCF, will determine whether or not this team is for real. A win against UCF in Orlando on Nov. 17 would be a big statement for head coach Luke Fickell and his staff. -- VanHaaren
No. 21 South Florida
Sure, the Bulls are undefeated. But the truth is, the Bulls haven't looked very dominant on their way to that undefeated record. They have played down the level of competition in close wins over East Carolina (2-4) and Tulsa, and needed (1-5) and needed fourth-quarter comebacks to beat the aforementioned Golden Hurricane and Illinois (3-3). The Bulls remain one of the most penalized teams in the country, and their special teams mistakes have nearly cost them once again. The most difficult part of the schedule comes in the second half, when they have to play Houston, Cincinnati, Temple and UCF. Getting more efficiency from quarterback Blake Barnett is a big key. -- Adelson
No. 22 Mississippi State
Bouncing back from back-to-back losses to beat Auburn looked good at the time, but not so much now that the Tigers are circling the drain. If State is heading in the right direction and hopes to play the role of spoiler against LSU and Alabama, the offense must improve. Quarterback Nick Fitzgerald, in particular, needs to do more than run the football. He hasn't thrown a touchdown or passed for more than 100 yards in either of his last two games, and that just isn't going to cut it. -- Scarborough
No. 23 Wisconsin
The Badgers are coming off their most lopsided loss since the 2014 Big Ten championship game, which puts in doubt not only their own chances to win a conference title this year but also whether they will be respected enough in December (should they win the West) to give a perception bump to a potential playoff contender from the East. Paul Chryst's team doesn't have the goods to make a playoff run in 2018. After being pushed around Saturday, the Badgers will have to spend the rest of the season rehabbing their credibility as a team that presents a formidable challenge to the Big Ten's best at the line of scrimmage. -- Murphy
No. 24 Michigan State
Can this Spartan run defense continue to be dominant enough to keep the Spartans in a heated race for the Big Ten's East Division? Injuries have robbed Michigan State's offense of any firepower, but a team averaging only 26.6 points per game has nudged its way back into contention by frustrating opponents and keeping games close. Clear answers about their ceiling might come as soon as this weekend. -- Murphy
No. 25 Washington State
The Cougars haven't won the Pac-12 since sharing the title with USC in 2002. That drought wasn't expected to end this season, but at this point the Cougars are as well-positioned as anyone. With ESPN's College GameDay in town this week for the first time, can the Cougars secure a program-altering win? If they do, they would be on course for one of the best seasons in school history. -- Bonagura