In rainy, windy conditions, USC and Notre Dame were locked in a close game late in the second quarter, before 17 seconds and a big helping of Trojan superstar Adoree' Jackson changed everything.

Jackson, the Trojans' playmaking junior defensive back, scored three touchdowns, including a 55-yard punt return late in the first half, and 17 seconds later, Ajene Harris returned an interception 33 yards for a touchdown to jumpstart No. 12 USC's 45-27 win over Notre Dame on Saturday at Memorial Coliseum in Los Angeles.

Jackson had USC fans chanting "one more year" after he scored his third touchdown of the game, a 97-yard kickoff return that featured a hurdle over Notre Dame's kicker and led the Trojans to their eighth straight win.

Jackson also caught a 52-yard touchdown pass from quarterback Sam Darnold for the Trojans (9-3), who failed to earn a spot in the Pac-12 championship game against Washington when Utah beat Colorado on Saturday night.

A Pac-12 title seemed like a pipe dream after the Trojans got off to an 0-2 start in conference play and finished September at 1-3, including a blowout loss to Alabama.

But coach Clay Helton stayed the course, made a change a quarterback and turned around the Trojans' season.

"I wish the September month would have been different," USC coach Clay Helton said. "But it is what it is."

Notre Dame went in the opposite direction and lost for the fourth time in the last six games to end a troublesome 4-8 season that included issues on and off the field.

On Saturday, defensive lineman Jerry Tillery committed two unsportsmanlike acts. First, the sophomore kicked an injured Trojan who was on the ground in the head. Later, Tillery appeared to intentionally step on the hand of another USC player, drawing a flag.

"You just can't do stupid things like that," Notre Dame defensive lineman Jarron Jones said of Tillery's actions. "That's going to reflect on you as a player. That's going to reflect on your character."

The loss and dirty plays concluded what has already been an ugly week for the Irish. On Tuesday, the NCAA ruled Notre Dame must vacate 21 wins, including all 12 from their undefeated regular season in 2012, the result of an academic misconduct case. Pending an appeal, they'll also lose their nine wins from 2013.

Despite the distractions, Notre Dame came to play early against USC. Josh Adams' 74-yard run set up the Fighting Irish's first touchdown, a 1-yard plunge by quarterback DeShone Kizer for a 7-3 lead early in the first quarter.

"These kids fight every day," said Notre Dame coach Brian Kelly, who added that he wanted and expected to be back to coach the Irish next season.

"One side of me says, 'look, this is my 25th year, I know what I'm doing,'" Kelly said. "But on the other side of it, you can't be surprised that when you go 4-8, that you're going to get those questions asked as well."

Even after giving up the 14 points right before the end of the first half, the Irish were still in the game and made a play on special teams to open the second half. Notre Dame capitalized on Jackson's fumble on the opening kickoff of the second half and cut the USC lead to 24-14 on a touchdown pass from Kizer to Chris Finke.

Jackson would make amends on the Trojans' next possession, scoring his first offensive touchdown of the season on a pass from Darnold.

"That was probably the most fun game I've ever been a part of," Jackson said. "The crowd was loud, and we were having so much fun out there."

Darnold, who was inserted as the starter a month into the season, completed 19 of 29 passes for 205 yards and two touchdowns, including a 2-yarder to JuJu Smith-Schuster that put the Trojans in command, leading 45-21 with 9:40 left in the third quarter.

"What an accomplishment by a group of kids that have been through some adversity and come out the other side of it," Helton said. "What this team and this group have is something special."

Kizer finished 17 of 32 for 220 yards with two touchdowns and an interception for the Irish.

Jones finished with 134 yards on 16 carries for USC.

NOTES: Notre Dame coach Brian Kelly called the NCAA penalty in academic misconduct case "discretionary" and "clearly excessive." ... The game was the last for USC's horse mascot Traveler. .... Adoree' Jackson's punt return for a touchdown was the fourth of his career, tying him for most in USC history. ... Referee Ron Cherry was injured in a collision with a USC player and had to leave the game in the third quarter. ... Notre Dame leads the all-time series 46-36-5.