For three quarters, this was ugly. Really ugly.

USC was clinging to a 5-point lead over significant underdog UNLV while sputtering on offense and starting to splinter on defense.

Much ballyhooed freshman quarterback JT Daniels and most of the Trojans' wide receivers not named Amon-Ra St. Brown had looked out of sync. The offensive line needed only a couple series to get the fans grumbling again.

And after a strong start, the defense started to get gashed on the ground. UNLV had already piled up 242 rushing yards through those first three quarters, which was more than USC had allowed in all but two full games last season.

Then the fourth quarter started, and Daniels again was slinging the ball liked he did a few weeks ago here at the Coliseum in the Trojans' first scrimmage -- the day he all but solidified the starting job in the eyes of many. He again looked like the freshman phenom who could change a game at any moment.

Which is exactly what he did on the way to an eventually lopsided 43-21 season-opening win over the Rebels.

"It's goosebumps running out there seeing the whole stadium, all these fans," Daniels said afterward. "... It's hard to put in words what it's like to run out there, hear everybody cheering for you."

The cheers were still reverberating as Daniels walked through the tunnel toward the locker room after it was all over, after he completed 22 of 35 passes for 282 yards and a touchdown in his collegiate debut. He wore a white USC hat a stoic gaze as fans on both sides of the tunnel chanted "JT, JT, JT."

For all the hype and expectations, all the write-ups in the national media before he had even thrown a college pass, Daniels was still a young freshman seeing the Coliseum on game day of the first time.

"Oh yeah, there's nerves," he admitted later.

Eventually, though, he was the dynamic downfield playmaker everybody was hoping to see.

On the first play of the fourth quarter, Daniels stepped up in the pocket and unfurled one of those seemingly effortless spirals he had made routine throughout fall camp, this time hitting St. Brown right in stride for a 43-yard touchdown strike.

The former Mater Dei High School teammates clearly have a heightened chemistry, which was on display again Saturday in the Coliseum. As Daniels struggled to connect with Tyler Vaughns and Michael Pittman Jr., there was St. Brown, racking up catches like a steady veteran.

Though, St. Brown downplayed the spark he provided early.

"I was rotating with Michael and it was my time to go up," he said simply.

Still, the USC offense didn't fully come to life until that touchdown connection from Daniels to St. Brown to open the fourth quarter. That pushed the Trojans' lead to 26-14 and created some long-awaited momentum.

"Coach Helton made it clear that I'm not here just to hand the ball [off] and throw the short pass every single time," Daniels said while recounting his strong finish.

After a quick three-and-out forced by the USC defense, Daniels shook off a second-down sack (and had a fumble overturned by review) and then did it again. This time his strike down the seam glided right into the arms of redshirt sophomore Trevon Sidney for a 41-yard gain down the UNLV 15-yard line. Aca'cedric Ware finished from there for a 15-yard touchdown run and a 32-14 lead.

"It was more of an intermediate play called and Trevon was my one deep option, but we have that alert when they got a safety lined up close and you've got a great receiver like Trevon Sidney we can take that shot," the quarterback explained.

Just like that, three ugly quarters turned into a comfortable fourth-quarter lead while Daniels almost doubled his passing yards from 144 through the first three quarters to 138 in the final period, including a 36-yard completion to Pittman on another downfield shot.

"You want to be able to get that chemistry a little bit sooner," Helton said. "The thing I'm really happy about, that game could have gone a different way if we didn't play clean football. No turnovers, only four penalties for 38 yards. ... The kids just stayed patient, they didn't make mistakes, they didn't make the critical errors. They played nice sound football and just let it come to them. And then all of a sudden things started breaking open a little bit, and then you look up and you have a 500-yard day (501 to be exactly) and over 40 points."

St. Brown had seven catches for 98 yards and a score while Sidney, who had just three catches for 35 yards last season, finished with three receptions for 72 yards Saturday.

Ware finished with 100 yards and a TD on 10 carries. Sophomore tailback Stephen Carr totaled 57 rushing yards on nine carries along with a 73-yard kickoff return in the second quarter, which amounted to one of the early missed opportunities as USC only went backwards after starting at the Rebels' 23 and settled for one of Chase McGrath's five field goals. And Vavae Malepeai added 48 yards and two touchdowns on eight carries.

Meanwhile, McGrath tied the program's single-game record with his five field goals.

The strong finish erased the tension from the game, but it probably won't erase the concerns. This was, after all, against a UNLV team that went 5-7 last year, and USC has its first big conference test next weekend at Stanford.

The offensive line has to be better. The special teams, which featured multiple ugly punts and yielded a fake punt first down conversion to the Rebels, has to be much better. That 36-yard rush on the fake punt set up a UNLV touchdown and a 14-9 lead for the visitors early in the third quarter.

While scattered with highlights, including five sacks, the defense was still too vulnerable. UNLV took an early 7-6 lead on a 71-yard Lexington Thomas run against a total defensive breakdown and finished with 308 rushing yards overall.

And the offense has to do this for more than one quarter. But in the fourth quarter, the potential for the unit and its much-hyped freshman was plain to see.

"Good game, good win, 1-0 on the week, but we've got a lot to fix before we get to Stanford next week," Helton admitted.