Halliday completed 58 of 89 passes for 557 yards and four touchdowns — but the Cougars still lost, 62-38, to the Ducks on Saturday night.
His attempts broke the FBS-level record of 83 set by Drew Brees for Purdue on Oct. 10, 1998 against Wisconsin. Halliday's total attempts and completions also broke the Pac-12 records set by Arizona's Matt Scott last season, and his total yards set a Washington State record.
It was his second career 500-yard game.
"I knew going in, on about Monday of last week, that we were going to throw it a lot. I mean, nobody ever thinks 89 is going to be the number," Halliday said. "Oregon is so athletic up front and so athletic at the linebacker position, they don't give us many run looks and running the ball isn't what we do best offensively.
"So we were just doing what we thought would be the most successful for us, which was to chuck it around."
Indeed, Washington State (4-4, 2-3 Pac-12) ran for just 2 net yards against the Ducks (7-0, 4-0).
Marcus Mariota threw for 327 yards and two touchdowns and ran for another for Oregon, who wore pink helmets, cleats and socks for Breast Cancer Awareness Month. Byron Marshall ran for 192 yards and three more touchdowns for the Ducks.
Mariota had his first two turnovers of the season, two fumbles that led to first-half Washington State touchdowns, and the Cougars pulled to 27-21 in the second quarter.
The Ducks cleaned up the mistakes in the second half and pulled away, racking up 719 yards in total offense. Freshman Thomas Tyner ran for 99 yards and two touchdowns.
"Oregon is a great team, and a fast team, and fundamentally sound. They don't make mistakes and we gave them too many opportunities," Cougars safety Deone Bucannon said.
The Ducks were coming off a 45-24 victory over Washington in Seattle last weekend. After Stanford's upset loss to Utah last week, undefeated Oregon is alone in first place in the Pac-12 North.
The Cougars were coming off a 52-24 loss to Oregon State in Pullman. The Beavers outscored Washington State 28-0 in the fourth quarter and Halliday threw three interceptions
After Mariota opened with a 57-yard touchdown dash, Marshall plowed across the line for a 1-yard touchdown midway through the first to up Oregon's lead to 13-0. Halliday found Dom Williams in the corner of the end zone with an 11-yard scoring pass, but Marshall answered with a 26-yard scoring run to make it 20-7.
Tyner made an acrobatic catch to get to the Washington State 1, then powered into the end zone for the touchdown early in the second quarter.
Mariota was sacked and his fumble was recovered by Washington State, leading to Halliday's 22-yard pass to River Cracraft for the freshman receiver's first touchdown.
He was sacked and fumbled again on the next series and Xavier Cooper scooped up the ball and ran it in to narrow the score to 27-21 with 5:35 left before halftime.
Tyner scored on a 66-yard run for the Ducks before Andrew Furney kicked a 49-yard field goal for the Cougars as time ran out to make it 34-24.
Mariota found Keanon Lowe with a 10-yard scoring pass and Marshall scored on a 30-yard run in the third quarter before Mitchell's pick six early in the fourth.
Halliday threw an 8-yard touchdown pass to Gabe Marks with 3:48 left and added a 3-yard scoring toss to Bobby Ratliff with 11 seconds to go for the final margin.
Halliday's passing yards surpassed Alex Brink's Washington State record of 531 against Oregon State in 2005.
The Ducks extended their winning streak over the Cougars to seven straight.
Washington State defeated a ranked opponent earlier this season when they beat then-No. 25 USC 10-7, although it was before the Trojans fired head coach Lane Kiffin. The Cougars have not defeated a team in the top five since 2003, when they downed No. 5 Texas 28-20 in the Holiday Bowl.
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