BERKELEY, Calif. (AP) -- Describing Deltha O'Neal as a cornerback and a return specialist doesn't begin to convey his impact. The California star is a rare game-breaker and big-play artist.

O'Neal returned an interception 67 yards for a touchdown and then set up a field goal with a 60-yard punt return as California sent Southern Cal to its fourth straight loss, 17-7 Saturday night.

"Deltha took over as usual," Cal coach Tom Holmoe said. "I can't say enough about him. He's just so spectacular out there, and I don't know what we would do without him. He's been terrific. He's not the solo star, but he's awfully bright."

The interception was O'Neal's sixth of the season and the school-record third he's returned for a touchdown. He also finished with 127 all-purpose yards and had a key fourth-down stop late in the fourth quarter, tackling Marcell Almond for a 1-yard loss to give the ball to Cal on downs and help run down the clock.

O'Neal said his play reflects Cal's aggressive defensive approach.

"That's our mentality," he said. "We come in thinking, 'OK, we have to score.' We don't even think about the offense. We're just thinking about the defense, three and out or get a 'pick, a fumble or sack the quarterback. We have to score and make big plays, from the defensive tackle to the safety."

The Trojans (3-5, 1-4 Pac-10) couldn't cope with it and fell into their longest losing streak since finishing 1991 with a six-game slide. They must win three of their last four games to be eligible for a bowl and avoid just their third losing season since 1961.

"I think this is obviously a difficult time but we have four games left," USC coach Paul Hackett said. "It's too bad we've got ourselves in such a hole.

"This is a good football team. We just have to find a way to win a game," added Hackett.

O'Neal was at the center of a punishing defensive effort that bottled up the Trojans' attack throughout the game. Cal defenders racked up nine sacks, including four by Mawuko Tugbenyoh, and forced USC into four turnovers while sending starting quarterback Mike Van Raaphorst to the bench in the second half for ineffectiveness.

"We told our team going in the three things we needed to do were control (O'Neal) on returns, confuse their offense and don't turn the ball over," Hackett said. "We couldn't do that."

Kyle Boller recovered from two interceptions to help cut off a USC rally by throwing a 33-yard touchdown pass to Ronnie Davenport with 14:53 remaining as Cal (4-4, 3-2) completed just its second sweep of the Los Angeles schools in 41 years. The Bears beat UCLA 17-0 two weeks ago.

The Trojans were trailing 10-0 and their best drive of the day had just ended in their third turnover when Sultan McCullough fumbled at the Cal 17 but they managed to get back in the game.

On a flea-flicker play, safety Ifeanyi Ohalete intercepted Boller's underthrown pass.

Four plays later, John Fox, who had replaced the struggling Van Raaphorst, connected with Kareem Kelly near midfield and the freshman receiver broke a tackle and faked his way past another defender en route to a 72-yard touchdown with 6:08 left in the third period.

Cal's offense, stalled most of the day, answered with Boller leading a 68-yard drive ending in the scoring pass the wide-open Davenport.

The Trojans mounted another threat only to turn the ball over again. Antoine Harris fumbled at the end of a 25-yard reception and Jamaal Cherry recovered for Cal at the Bears' 42 with 8 1-2 minutes left.

O'Neal, who had his school-record third interception return for a touchdown this season in the second quarter, broke loose on a 60-yard punt return to set up Mark Jensen's 37-yard field goal for a 10-0 Cal lead early in the third.

Trojans cornerback Antuan Simmons gave life to a Cal drive with a fourth-down pass interference penalty but then came back to stop it, intercepting Boller's overthrown pass in the end zone.

Aided by two personal foul calls, the Trojans quickly advanced to the Cal 40 before Bears' defense thwarted them again.

With defensive end Andre Carter in his face, Van Raaphorst hurried a sideline throw and O'Neal saw it coming. He stepped in front of Southern Cal receiver Windrell Hayes, grabbed the interception, his sixth of the season, and took off down the left sideline.

Van Raaphorst and Hayes gave chase but didn't come close to catching O'Neal.