SEATTLE (AP) Elijah Molden dropped into open space near the goal line and went unnoticed. When the pass went his direction, Washington's young cornerback finally grabbed his first interception. Two plays later, Salvon Ahmed ran into open space. When he found it, the speedy running back broke off the longest run play for Washington in 25 years.

They were two plays a matter of seconds apart that broke the game open and helped No. 17 Washington beat No. 21 Southern California 28-14 on Saturday.

''I thought that was game-changing, that sequence right there. That's a 14-point swing,'' Washington coach Chris Petersen said.

Washington's talented secondary forced Matt Fink into three interceptions, shut down the pass game for most of the afternoon and caused headaches for the former third-stringer thrust into his first college start.

Meanwhile, the Huskies received a career day from Ahmed, who rushed for 153 yards, including his 89-yard TD run in the third quarter and gave Washington a 21-point lead. Ahmed missed last week's win at BYU with a leg injury. But he was back in a big way against the Trojans with the longest run play for Washington (4-1, 1-1 Pac-12) play since a 91-yard TD run by Napoleon Kaufman in 1994 against San Jose State.

''Those are the kinds of runs that you dream for,'' Ahmad said. ''I'm happy that I've got an offensive line that can make those things happen up front for us. They work their tails off every single down and that is a reward to them and a reward to me.''

His big run came moments after Fink's most critical mistake.

With USC (3-2, 2-1) trailing 20-7 and driving, Fink failed to see Molden dropping into a zone and had a pass intercepted at the Washington 1 as he tried to hit Michael Pittman Jr.

''It was just a high ball and I jumped up and got it. It could have been anyone,'' Molden said.

Each of Fink's first two interceptions led to Washington touchdowns, and his final one - the second of the day for freshman safety Cameron Williams - came in the closing seconds. But it was Molden's pick that stung most.

''It was just a bad read. Should have handed the ball off and that's on me,'' Fink said.

Fink, the No. 3 QB when the season started, carved up Utah a week ago throwing for 351 yards after being called into duty when Kedon Slovis went down with a concussion. Fink found passing quite a bit tougher against Washington and its standout secondary.

The Trojans found nothing open downfield. Pittman caught a 44-yard touchdown on a blown coverage late in the third quarter. It was the Trojans' first pass play of more than 8 yards and was the only one of longer than 19 yards. USC's last legitimate hope ended when Myles Bryant broke up a fourth-and-goal pass in the end zone with 4:47 left.

Washington defensive coordinator Jimmy Lake threw looks at Fink that hadn't been shown all season. The Huskies used bracket coverage on Pittman and Tyler Vaughns regularly and the Trojans didn't have answers.

''Those are some of the best receivers in the Pac-12. I've been competing against those guys for a long time, but we came in understanding they were going to test us,'' Bryant said. ''They ended up getting one on us but I think guys played big and we ended up getting turnovers and helping our offense out.''

Fink finished 19 of 31 for 163 yards and had a 3-yard TD run. Stephen Carr rushed for 94 yards, but for this day USC's version of the `Air Raid' offense was grounded.

''We made enough mistakes to lose the game,'' USC coach Clay Helton said.

After a couple of big weeks, Washington QB Jacob Eason had a quiet day but didn't make any mistakes. Eason was 16 of 26 for 180 yards.

FIRST QUARTER DOMINANCE

Washington took an early 14-0 lead, continuing its first-quarter dominance this season. The Huskies took advantage of a short punt and capped a 35-yard scoring drive with Newton's 1-yard TD plunge. Fink followed with a bad overthrow that was intercepted by Williams and Washington built a two-touchdown advantage when Andre Baccellia recovered Ahmed's fumble in the end zone. Ahmed fumbled at the 1, but Baccellia won the scramble and gave the Huskies a 14-point lead.

Washington has outscored opponents 77-3 in the first quarter this season.

THE TAKEAWAY

USC: The Trojans were unable to get Pittman free a week after he caught 10 passes for 232 yards against Utah. Pittman didn't get his first target, and catch, until midway through the second quarter. He finished with four catches for 64 yards, but 44 came on one play.

Washington: Ahmed's previous career high came earlier this year when he rushed for 119 yards against California. The Huskies rushed for 193 yards as a team.

POLL IMPLICATIONS

USC's return to the AP Top 25 is likely to be brief. The Huskies have a chance to move up a couple of spots from last week.

UP NEXT

USC: The Trojans have an open week before playing at Notre Dame on Oct. 12.

Washington: The Huskies begin a two-game road trip playing at Stanford next Saturday.

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