Lincoln Riley needed only three words when asked last Saturday if he still had confidence Alex Grinch was the right defensive coordinator to help the Trojans get where they want to go.

"Yes, I do," Riley said after the 48-41 win at Colorado.

The defensive progress (or lack thereof) the rest of the season will be a primary storyline every week the rest of the way for a USC team that faces a slew of potent offenses over the second half of the schedule.

The No. 9-ranked Trojans' opponent Saturday night, Arizona, is one to take seriously as well. Even though the Wildcats (3-2, 1-1 Pac-12) rank a modest 44th nationally in total offense (428.8 yards per game) and are likely rolling with a backup quarterback in Noah Fifita would be making just his second career start, they pushed USC into a shootout last season in Tucson -- a 45-37 Trojans win.

RELATED: Matchup breakdown and perspective from our Arizona insider | Five storylines for USC-Arizona | PODCAST: Taking a hard look at Arizona's defense with analyst Max Browne | FILM ROOM: Breaking down what went wrong for USC's defense vs. Colorado

But the bigger point is that there is little relief for the Trojans' defense the rest of the way with the current No. 1 and 2-ranked offenses in college football -- Washington and Oregon -- looming as marquee showdowns with Notre Dame (25th nationally) and UCLA (28th) also ahead.

"We’re fighting, scratching, clawing. Not hiding under our desk. Excited for another one this weekend," Grinch said this week, as the USC defense looks to bounce back from its worst statistical showing (564 yards) in his time with the program.

The Trojans' defense will be the most scrutinized storyline Saturday night as USC (5-0, 3-0) looks to not only stay unbeaten but show that it has more to rely on the rest of the way than just its bevy of offensive stars.

Kickoff is set for 7:30 p.m. PT in the Coliseum (on ESPN). First, our TrojanSports.com staff came together for it weekly roundtable debate/discussion to cover all the relevant storylines and make our predictions.

Who are the three most important players the rest of the season for USC’s defense to improve?

Ryan Young: "I think it starts with Mason Cobb proving he can be a difference-maker at middle linebacker. The coaching staff has made clear he is the one constant at the two inside linebacker spots, while the other remains in flux or as a rotation. Cobb is coming off an encouraging performance with 13 tackles, 2 tackles for loss and a pass breakup at Colorado, but he hasn't yet truly popped in the way many expected when USC landed him out of the transfer portal from Oklahoma State. The Trojans need a game-changer in the middle of the defense and Cobb will get every opportunity to prove he can be that. I'll go with Bear Alexander, who has been disruptive at defensive tackle with 15 pressures through five games. But I still don't think we've seen his peak yet. If he can be a true wrecking ball in the middle of the defensive line the rest of the way, that helps the edge rushers, the linebackers and the secondary. He's the best talent up front and thus definitely one of the most pivotal defensive players moving forward. And for my third pick, I'll go with Domani Jackson or Ceyair Wright. Jackson's status for Saturday night seems in question, but this is a bigger picture answer anyway. Christian Roland-Wallace is going to man one of the corner spots the rest of the way, but the Trojans need stability on the other side and they haven't gotten it yet. Jackson may have the best upside as a blazing fast five-star talent, but he's also given up the most big plays so far this season. Wright received such positive buzz through the spring and fall camp from coaches -- I'd like to see if he can assert himself there and carry those practice performances over to Saturdays."

Jeff McCulloch: "The three most important players for this defense for the rest of the season are Mason Cobb, Bear Alexander and Christian Roland-Wallace. Alexander has been a monster on the interior of the line this season, giving offensive lines problems every single snap. The crazy thing is, I think there is another gear in Alexander that he hasn’t reached yet. As long as he continues to be in the backfield consistently, he can help hide the shortcomings of the defensive backs. Now, Mason Cobb is the true leader of this defense and he showed it last week against Colorado. While the defense ended up struggling at the end of the game, Cobb did not. He had his strongest game of the season and even he wasn’t satisfied with his performance, feeling he left a lot more on the table. If he can help get everyone aligned pre-snap, he will help this team more than just his performance. And Roland-Wallace needs to be this year’s Mekhi Blackmon, and it's starting to look like that’s exactly what he is going to be. USC needs a shutdown corner that can take away half the field in the passing game. The veteran has the talent to do that and five games in, it seems like he has finally found his footing. If Donte Williams only has to worry about the second cornerback position, that makes his life a lot easier and he can truly hit on the small techniques that can help the cornerback room grow. This defense needs so many guys to truly step up, but if the leaders of this team improve their game noticeably, the others will follow."

Tajwar Khandaker: "Bear Alexander is the key to everything for the USC defensive front. Though the talent across the board has improved on the defensive line, nobody provides the kind of presence that Alexander does in the middle. His size, power, and explosiveness at the defensive tackle position are unique and raise the defensive floor by several notches whenever he’s on the field. He’s already been a big-time difference-maker, but Alexander still shows a lot of room for development; his continued improvement could help the Trojans to better control games from the front seven on the defensive side of the ball. Next up is Eric Gentry, who’s the most talented and well-rounded of the USC linebackers, in my estimation. Gentry’s ability to impact the game as both an instinctive run-defender and as a natural in pass coverage gives him the potential to anchor the middle of the field for the Trojans in a way that I don’t think anyone else can replicate. Gentry’s injury issues have held him back from nailing down a starting position as of yet, but I find it hard to believe that he won’t secure one in the near future. Gentry’s tackling isn’t yet a strength of his game, but his all-around play should help to stabilize things at the second level for the Trojan defense. Finally, Domani Jackson has the potential to be one of the key components to sustained defensive improvement for this team at the cornerback position. The Trojans don’t have a clear standout at the position right now, but Jackson is easily the most physically talented of the bunch. His speed/size combination on the boundary is special, theoretically allowing him to match pretty much any receiver in the country down the sideline. Jackson is still quite raw, and he’s been picked on a bit as a result in the early season. Nonetheless, he’s made a number of strong plays when targeted, and there’s every reason to believe he’ll continue to grow more confident in his technique and assignments as the weeks carry on. If Jackson (regardless of whether he plays Saturday) can start to play with some more composure out wide, he could very well become the team’s best cover-man by the season’s end."

What is your regular season record projection for USC at this point?

Ryan: "Logic would dictate 10-2 based on what we've seen so far, but I'm still going to stick with 11-1. I've been very clear this week that I've started to lose confidence in the direction of the defense (yes, much later than everybody else), but I still haven't thrown in the towel on the group. They have enough talent if they can get out of their own way (missed tackles, blown gap assignments, cornerbacks allowing big plays despite being in position to do better, etc.) I don't know that it will happen, but there is still the potential for this unit to be adequate enough the rest of the way and do enough to complement the Trojans' high-powered offense, which is ultimately, of course, what drives my confidence. I would bet on Caleb Williams every week over any other quarterback, coach, team or matchup. I think MarShawn Lloyd is the best running back in the conference. I don't think we've seen freshman phenom Zachariah Branch fully unleashed yet. In short, I believe this will end up as the best offense in the country, capable of winning shootouts if needed more times than that. And I maintain some degree of lingering hope that the defense can deliver just enough."

Tajwar: "10-2 sounds right to me unless the Trojans defense takes some significant steps forward. The explosiveness of this offense should be enough to pace scoring with any of the opponents on USC’s schedule, and the strength of the pass rush (if nothing else) on the defensive side should make a reliable impact. Even if that formula works most of the time the Trojans will be rolling the dice; a day where the offense is just a little below its normal standards might be enough for the team to drop a contest against the likes of Washington or Oregon. If the overall quality of the defense doesn’t change much from what we’ve been saying, I think it’s likely that the team stumbles once or twice against the strength of opposition they’ll be facing."

Jeff: "I think USC can be a 1-loss team. Their matchup at Notre Dame is going to be a massive game where I can see the Trojans slipping, especially on the road. In the two road games so far this season, the team has struggled against inferior teams. Notre Dame is as good if not better than USC. But this team is so unpredictable. They can go undefeated this season, or they can lose 3 games. It’s really hard to get a fair read. I’ve said this before and I’ll say it again, this defense has the talent to be a solid defense -- it just needs to be put in the right spots and execute."