If No. 21 Southern California even hopes to think about a big finish to its disappointing season, the Trojans realize they must improve quickly and significantly on defense.

The good news? That shouldn't be too tough.

After the worst defensive game in USC history last week, almost anything at all would be an improvement Saturday against Arizona State.

"I don't think we're ever going to play a game like that again," USC safety T.J. McDonald said after the Trojans allowed 730 yards and 62 points in a loss to Oregon.

USC (6-3, 4-3 Pac-12) hosts the slumping Sun Devils (5-4, 3-3) at the Coliseum in what's essentially an elimination game for the Pac-12 South title. The Trojans haven't lost three straight games since 2001, when Lane Kiffin was the Trojans' 26-year-old tight ends coach under Pete Carroll.

"We all know we've got to get better," Kiffin said. "We have to look at ourselves, always, when anything is that lopsided."

The Trojans went back to work with determination this week after that embarrassing defensive effort against Oregon in their second straight loss. They also endured another round of the off-the-field shenanigans that seem to surround this program, this time the dismissal of a student manager for underinflating footballs before that loss to the Ducks.

USC's defense appeared overwhelmed by the Ducks — and while they're hardly alone there, the result was discouraging for the players and coaches who must try to keep up with Arizona State quarterback Taylor Kelly and his solid offense this week. The Trojans have yielded 1,318 yards and 101 points in their last two games.

"When you perform like we did, it's totally unacceptable," USC defensive coordinator Ed Orgeron said. "We did not play well. I did not coach them well, and we've got to get better. There's no excuse for it. ... It's hard, especially during the week, when you're representing a great program like USC, and you feel like you let everybody down. We've got to deal with it. We can't let this happen to us twice."

Not everything has been awful for the Trojans lately: The offense led by Matt Barkley and receivers Robert Woods and Marqise Lee has scored at least 36 points in four of the last five games, following much the same path of gradual maturity shown by last season's offense.

"We're starting to come together," center Khaled Holmes said. "I think we've played better each week. We're still not where we want to be, but you can see the progress."

But the Trojans will face the Pac-12's best pass defense when Arizona State goes after its first win in Los Angeles since 1999.

"They're very simple in what they do, unlike the teams we've faced over the last three weeks who are all over the map with their looks," said Barkley, who has thrown four interceptions in the past two weeks. "This week, it will be much simpler, but they are very good at what they do."

Although the Sun Devils have lost three straight after a 5-1 start under new coach Todd Graham, they're still in the running for postseason play. Graham insists Arizona State isn't headed for another late-season swoon matching last year's five-game skid, which cost Dennis Erickson his job.

"They have had many opportunities in the last three weeks to implode or to take a step backward, but they haven't done that," Graham said of his players. "And that is first and foremost what we committed to our fans. This program is going to be out winning championships, and we are going to have the same expectations. The season isn't over, is what I would tell (fans)."

The Trojans also have motivation for the matchup from last season, when the Sun Devils largely shut down Barkley in a 43-22 victory, snapping an 11-game skid against USC.

"We remember that game, but we've still got a lot of games to play this season," Woods said. "We could still win out and get to where we want to be, but we're not getting ahead of ourselves."


AP College Football Writer John Marshall in Phoenix contributed to this report.