BERKELEY, Calif. -

Colin Ellis returned two interceptions for touchdowns in the second half, helping No. 22 Northwestern beat Cal 44-30 on Saturday night at Memorial Stadium and ruining the debut of Sonny Dykes as the Bears' head coach.

Both of Ellis' picks came off tipped passes thrown by Jared Goff, the first true freshman in history to start a season opener for the Bears.

Ellis' first interception came in the third quarter, and he returned it 56 yards to give the Wildcats a 27-24 lead. His second came in the fourth quarter, and he returned that one 40 yards to boost the Wildcats' lead to 37-27 with 7:57 to go.

Cal reduced the margin to 37-30 on Vincenzo D'Amato's 37-yard field goal with 4:45 left, and the Bears regained possession on an Alex Logan interception at the Northwestern 49.

But Ibraheim Campbell intercepted a Goff pass at the Wildcats' 9-yard line with 3:42 remaining, and the Wildcats then marched 91 yards for the clinching score.

Goff put up good numbers, completing 38 of 63 passes for 445 yards and two touchdowns in the spread offense that Dykes brought with him from Louisiana Tech, which led the nation in scoring and total offense last season. But the three interceptions were costly.

The Wildcats lost starting quarterback Kain Colter early in the first quarter to an upper body injury. As a result, Trevor Siemian, the passing half of Northwestern's two-quarterback system, handled the quarterback chores the rest of the game. He finished 18-for-29 for 267 yards, one touchdown and two interceptions.

Northwestern tailback Venric Mark, who rushed for 1,366 yards last season, was limited to 29 yards on 11 carries. But Treyvon Green ran for 129 yards and two touchdowns for the Wildcats.

Cal had two receivers with more than 100 receiving yards. Bryce Treggs had 13 catches for 145 yards and Chris Harper had 11 receptions for 153 yards and two scores.

Northwestern led 17-10 at halftime, with the passing of Siemian enabling the Wildcats to overcome an early 7-0 deficit. He completed 15 of 20 for 199 yards, one touchdown and an interception in the first half.

On Cal's opening possession, Brendan Bigelow runs of 19 and 33 yards helped the Bears get to the Northwestern 10-yard line, where they faced a fourth-and-5. The Bears lined up for a field goal attempt, but after taking the snap, holder Jackson Bouza flipped the ball back to kicker Vincenzo D'Amato, who tossed a short pass back to Bouza, who ran it in for the first score.

Northwestern tied it two minutes later, taking just five plays to go 75 yards. Green finished the drive by bursting up the middle on a 33-yard touchdown run.

However, Colter sustained an upper body injury during that drive and left the game.

That left the quarterback job to Siemian. He directed Northwestern on an 11-play, 68-yard scoring drive that ended with Siemian's perfectly lofted 19-yard touchdown pass to Tony Jones. That gave the Wildcats a 14-7 lead early in the second quarter.

Northwestern made it 17-7 on an 80-yard drive that started at the Wildcats' 3-yard line and ended with Jeff Budzien's 35-yard field goal.

Cal reduced the deficit to 17-10 on a 28-yard D'Amato field goal with three seconds left in the half, ending a drive that started at the Bears' 6-yard line.

NOTES: Northwestern CB Daniel Jones was taken off the field on a cart after suffering an apparent leg injury late in the first half. . . The only previous time Northwestern and Cal met was in the Rose Bowl after the 1948 season. Northwestern won that game 20-14 . . . Two Cal defensive starters -- DE Brennan Scarlett (hand) and ILB Nick Forbes (back) -- did not play in the opener because of injuries. No key Northwestern players missed the game with injuries . . . Coming into Saturday's game, Pat Fitzgerald carried a 7-0 record in season openers as Northwestern's head coach . . . The Wildcats wore white helmets for the first time since 1980.