The little things are starting to make a difference.
Learning the tendencies of the opposing quarterback, listening to his voice, anticipating the snap count.
Recognizing the offensive linemen and their quirks — which guys sit back in their stance or lean slightly to one side when a particular play is called.
A month ago, USC's defensive front seven — composed mostly of underclassmen — say they were worried about lining up in the right places. Now they feel confident enough to pay attention to tiny nuances.
"When you know what the guy in front of you is going to do, it helps," linebacker and defensive end Porter Gustin said. "Just knowing the little things."
Their improvement over the first five weeks translated into four sacks and a total of six tackles for losses on Saturday, the defense barging into Colorado's backfield to disrupt plays.
It couldn't have come at a better time.
The Trojans are desperate to turn around a season headed in the wrong direction and no team can put all of that weight on a new quarterback, even one as promising as Sam Darnold.
On an afternoon when Darnold and his group struggled with turnovers, the Trojans needed stops on the other side of the ball to secure a 21-17 victory over No. 21 Colorado.
"I have to give great credit and the game ball to our defense," Coach Clay Helton said. "Without them, I don't know if we win that game."
Their big day started early, on the game's first possession, when outside linebacker Uchenna Nwosu rushed hard and deflected a pass from Buffaloes quarterback Steven Montez.
A few minutes later, on Colorado's second drive, a strong push up the middle forced Montez to scramble right and misfire.
"They did a good job of blitzing us," Colorado Coach Mike MacIntyre said. "They did a good job tipping a few passes."
The Trojans' defensive scheme usually begins with three linemen and creates added pressure by bringing a linebacker. Sometimes the extra rusher comes from outside. Sometimes, he charges up the middle.
Defensive coordinator Clancy Pendergast has tried to change things around the last few weeks.
"Clancy's calls have been ultra-aggressive and he is mixing it up extremely nice," Helton said. "Mixing it up as a playcaller, I think it's keeping [the other team] in check and confusing quarterbacks."
As Nwosu put it: "That's always our plan, make the offense a little uncomfortable."
Against Colorado, that meant hurrying Montez into a costly intentional grounding penalty. It meant putting the quarterback on his back.
Gustin hit him from the blindside near the end of the second quarter, a collision that kept Montez out of the game for the remainder of the half.
"I got the air knocked out of me," Montez said. "Couldn't really breathe."
If defensive pressure helped USC build a 14-0 lead, it became critical later in the game when the Trojans turned the ball over three times in short order, giving Colorado's normally high-scoring offense a chance to get moving.
But Nwosu added to his career-high 10 tackles by chasing Montez out of the pocket and forcing an errant pass that turned into a leaping, twisting interception by cornerback Adoree' Jackson.
Then inside linebacker Cameron Smith hurried another throw that was nearly picked off by Iman Marshall.
USC will probably need that sort of effort to survive a stretch that includes winnable games against Arizona and Oregon, along with tougher matchups against California, Washington and UCLA.
As one of the veterans of his group, nose tackle Stevie Tu'ikolovatu would like to think the front seven is ready.
"We just kind of flipped a switch when we saw our record going the wrong way," the senior transfer from Utah said. "The young guys, they're learning to finish games."
Nwosu saved the biggest play for last.
With the Trojans clinging to a seven-point lead — and Colorado driving to USC's 22-yard line — he sacked Montez for a two-yard loss and forced the Buffaloes to settle for a field goal.
After that, the offense was able to run out the clock. USC had held Colorado to 96 yards rushing and 17 points, both well under the Buffaloes' season average.
With a victory over a nationally ranked team, and a record back at .500, Gustin thinks the defense can keep improving.
"Just being able to get the game experience," he said. "It makes a huge difference."