AP Game review
Last year, the Trojans beat the Irish 44-13 and knocked Notre Dame out of contention for a Bowl Championship Series game. This time, USC (6-1) remained in the national title race, while the Irish (2-4) are in danger of a losing season.
The Trojans rolled up 551 yards in beating the Irish on the road for just the second time since 1983.
Led by Leinart, who replaced Heisman Trophy winner Carson Palmer this season, Southern California scored on four of its first five possessions in getting off to its best start since 1995.
After each team scored on its first possession, USC scored 31 straight points against an Irish defense looking to avenge last year's poor effort when they allowed 610 yards.
Like Palmer, who passed for 425 yards against the Irish last year, Leinart dominated. He was 16 of 20 for 229 yards with the TD passes in the first half.
Leinart came out throwing, completing 10 of 13 for 142 yards in the first quarter, which ended with USC ahead 21-14. Leinart finished 26 of 34 with no interceptions.
Colbert caught eight passes for 120 yards on eight catches, and Williams had nine catches for 112 yards.
The Trojans picked up where they left off in last year's game, driving 80 yards on each of their first three drives. Leinart threw TD passes of 18 yards to Colbert and 7 yards to Williams before Bush ran 58 yards for another score.
USC went ahead 28-14 on Leinart's 3-yard TD pass to Dennis, and added a TD on the first possession of the second half - Leinart's 7-yard TD pass to Guenther.
The Irish, who had just 109 yards total offense against USC a year ago, finished with 279 yards Saturday. Julius Jones scored on a 22-yard run and Anthony Fasano scored on a 2-yard pass from Brady Quinn, who was 15 of 34.
The 45 points were the second-most for the Trojans against the Irish, off to their worst start since 1997.