Southern California had too many penalties, struggled in the red zone and found itself in a late hole for the second straight week.
The Trojans rallied to win a week ago and did it again with another pair of late scoring drives.
Resiliency has been the theme so far for USC in this pandemic-shortened season.
Vavae Malepeai bulled his way through multiple tacklers for an 8-yard touchdown run with 25 seconds left, and No. 20 USC beat Arizona 34-30 on Saturday.
“We have some things we need to get better at, but we're 2-0,” coach Clay Helton said. “A lot of teams would like to be in that position.”
USC (2-0, 2-0 Pac-12) was outplayed by Arizona State last week before scoring two touchdowns in the final three minutes of a 28-27 victory.
The Trojans again rallied late to win a game they were outplayed in for most of the afternoon.