August is here and that means college football season is starting soon. The first games of the 2017 season kick off Aug. 26. And as it quickly approaches, we have 25 days to preview each of the 25 teams in our updated Dr. Saturday 2017 preseason poll. Check here every day to find out who we think the 25 best teams in the country will be. Fair warning, however. We’re probably going to be wrong.

Previous entries: No. 5 Oklahoma, No. 6 Clemson, No. 7 Oklahoma State, No. 8 Penn State, No. 9 Washington, No. 10 Auburn, No. 11 LSU, No. 12 Michigan, No. 13 Stanford, No. 14 Louisville, No. 15 Wisconsin, No. 16 Georgia, No. 17 Florida, No. 18 South Florida, No. 19 Kansas State, No. 20 Texas, No. 21 Miami, No. 22 Notre Dame, No. 23 Northwestern, No. 24 Washington State, No. 25 North Carolina

No. 4 USC

2016 record: 10-3
Returning starters: 5 offense, 7 defense

Biggest non-conference game: Sept. 16 vs. Texas
Biggest conference game: Sept. 9 vs. Stanford

Key returning player: QB Sam Darnold
Key departed player: DB Adoree’ Jackson

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Three things to know about USC

• USC was a different team when Sam Darnold stepped onto the field last season. It’s scary to think he has room to improve.

The Trojans started 1-2 with Max Browne at quarterback when Clay Helton moved Darnold, just a redshirt freshman, into the starting lineup. He provided a spark for the Trojans offense on the road against Utah for his first career start. USC ended up losing that game on a late Utes touchdown, but it was clear the move to Darnold was the right one.

After that night in Salt Lake City, the Trojans did not lose again in 2016.

Now, after an off-season of glowing media profiles and other accolades, Darnold is firmly in the spotlight with the Trojans as Pac-12 favorites. Darnold improved on a weekly basis last year, capping off his stellar season with a ridiculous performance in USC’s comeback win over Penn State in the Rose Bowl. He threw for 453 yards and five touchdowns in the thrilling 52-49 victory to finish the season with 3,086 yards, 31 touchdowns and nine interceptions.

PODCAST: Pete Thamel on the Year of the QB

As our Pat Forde noted, Darnold has the brilliant ability to freelance and extend plays, but he is prone to forcing balls into tight spaces when it may be ill-advised. But when it looks like there’s nothing there, Darnold can pull the rabbit out of the hat and make a big play.

Plays like the one above in the Rose Bowl are what make Darnold a special player, but in 2017 he’ll be doing it with a lot of new weapons in his receiving corps.

Deontay Burnett is back in the slot, but JuJu Smith-Schuster and Darreus Rogers — the Trojans’ two leading receivers in 2016 — have moved on to the NFL. Steven Mitchell (68 career catches) is back from injury and talented tight end Daniel Imatorbhebhe will be nice options, but when asked about his major concerns at Pac-12 Media Days, Helton pointed to Darnold getting acclimated with the team’s array of young, inexperienced receivers.

“Probably the biggest (concern) is the chemistry between Sam and our new receivers. I think they’re beyond talented, the kids that we redshirted, but they haven’t been in real live games yet. And to be able to see those bullets fly and see how they react will be really important to us,” Helton said.

“I think the chemistry between that wideout corps and Sam will be ultra important. I thank God that Deontay is with us, and we’re getting Steven Mitchell off injury. And the tight end position with Daniel Imatorbhebhe and several others will play a big factor for us.”

Darnold does have the luxury of an awesome group of running backs playing behind him, led by Ronald Jones and Justin Davis, who combined for 1,689 yards last season. Jones, a junior, really got it going late in the year, rushing for at least 120 yards in four of the last five regular season games, including a 223-yard performance against Cal.

Another minor concern on offense is the continuity of the line, which replaces three all-conference players, including both tackles. But Toa Lobendahn, with 20 career starts, will return from injury at center and Helton has the luxury of plugging in Chuma Edoga, the No. 35 overall recruit in 2015, at one of the tackle spots. The unit should be just fine.

• The brilliance of Darnold and the offense kind of overshadowed how solidly the USC defense played during its long winning streak.

The Trojans played a lot of sophomores, who all return with that year of big-time experience under their belts. The defense is especially strong at linebacker with Cameron Smith in the middle and Porter Gustin and Uchenna Nwosu coming off the edge in Clancy Pendergast’s 3-4 scheme. Helton said Smith, who has 161 tackles in his two seasons with the program, is the “quarterback of the defense.”

As good as the linebackers should be, there are a few big holes to fill. At nose tackle, Utah graduate transfer Stevie Tu’ikolovatu made an even bigger impact than most anticipated, Leon McQuay was consistently solid at safety and Adoree’ Jackson was the big-play threat at cornerback and on special teams. Iman Marshall, who started opposite Jackson, returns as the Trojans’ top corner. Still, Jackson is a tough guy to replace.

“Adoree’ is — this is my 23rd year in college football — one of the more special players and people I’ve ever been around,” Helton said. “When you talk about a guy that’s a dominant corner, can help on offense, can do kickoff and punt return, that’s hard to replace.

“I think we have strength in numbers this year, really. We have some individuals that I think can help us at the corner position. We’ll be finding our punt returner and kick returner. I think we’ve got some awesome candidates in those two areas.”

Another concern is on special teams, where Matt Boermeester, who kicked the game-winning field goal in the Rose Bowl, was booted off the team. Michael Brown, a redshirt freshman, is the only scholarship kicker on the roster. He has been competing with walk-on Chase McGrath. It’s a tenuous situation.

“It’s been off and on,” Helton said earlier this month. “One day it’s been really good. And then today there’s some balls going everywhere.”

• USC enters the 2017 season from a different vantage point with expectations at a really high level. It’s a dramatic turnaround from last September when folks were wondering whether Helton would last the season. He has maintained he stayed true to himself amid the 1-3 start and that really helped change the course of the 2016 season.

“Part of being a head coach is having the trust and relationship with your players that when you are in adverse times, that they trust the process. They trust when you tell them they’re getting better each and every week, that they trust you’re saying the right things to them and being brutally honest with them,” Helton said.

“Probably the biggest thing I’ve learned last year, it’s not all about the X’s and O’s, it’s about the relationships with 18- to 21-year-olds and how important that is. Not in the good times, that’s easy; but when things, that adverse situation, comes up, how you deal with it.”

Helton said his team has “welcomed” the heightened expectations. The confidence built from last year’s run has equipped the team to handle it and thrive in it.

“I thought our maturity that we gained from Game 1 to the Rose Bowl really showed. If you look at us from Game 1, I thought we were an immature football team. And we learned how to win games,” Helton said.

“The reality is this, it’s easy to go from where we were to No. 3 in the country. It’s harder to go from third to one. And that’s our challenge right now. It’s going to take a lot of hard work during camp and a lot of young guys developing in a hurry for us to get there. But that’s always going to be our expectations, and we welcome them.”

USC was the perfect example of not overreacting to early season performance last year. But some of the team’s biggest games come in September yet again. The Trojans host Stanford in Week 2 and Texas in Week 3. A trip to Notre Dame comes in October during the meat of the Pac-12 schedule, but that looks like the most difficult game on the schedule after Stanford on Sept. 9.

The Trojans miss both Washington and Oregon this year. The schedule shakes out very favorably for a berth in the College Football Playoff, provided there are no major slip-ups.

For more USC news, visit TrojanSports.com.

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Sam Cooper is a writer for the Yahoo Sports blogs. Have a tip? Email him or follow him on Twitter!

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