After losing to Eastern Washington on Saturday, the Beavers vowed to let that happen again.
Vernon Adams passed for 411 and ran for 107 to lead Eastern Washington to a 49-46 victory over No. 25 Oregon State.
Eastern Washington became just the third FCS team to beat a ranked FBS team.
Sean Mannion threw for 422 yards and Brandin Cooks had 13 catches for 196 yards for the Beavers, who two seasons ago were similarly surprised by lower division Sacramento State and stumbled to a 3-9 finish.
"This loss doesn't define us as a team," Beavers running back Storm Woods said. "When we lost to Sac State people were really down on themselves, as opposed to this year."
Oregon State had 527 yards total offense. It was the defense that fell down on the job, as Adams gave the Beavers wits with his mobility and big-strike passing.
The junior from Pasadena, Calif., played with panache, throwing for four touchdowns and running for two, completing 23 of 30 passes despite leaving the game twice once with cramping and a second time after taking a hard hit near the sideline.
"It's just having swagger," Adams said. "Coming out here and not being nervous. Just come out here and play your game."
Adams scored on a 2-yard run to put the Eagles up 49-46 on their final drive. It was the first time a team from the FCS has defeated a ranked team from the FBS since James Madison beat Virginia Tech in September 2010. Appalachian was the first against Michigan in 2007.
Getting the ball back in the final seconds, Mannion led the Beavers down the field, completing two quick passes to give Oregon State a chance to tie, but Trevor Romaine's 52-yard field goal attempt was wide right.
Asked if he thought his team overlooked the Eagles, coach Oregon State Mike Riley was thoughtful.
"I don't. I don't," he said. "I think that would be a discredit to that kid playing QB and all the plays they made. I don't think that's it.' "
Ashton Clark had 155 yards receiving and Cooper Kupp had 119 yards and two touchdowns for the Eagles (1-0), who are ranked fourth in the preseason FCS poll and third in the coaches' poll. It was the school's first win over a Pac-12 opponent.
Eastern Washington went 11-3 last season and was the Big Sky Co-Champions before losing in the semifinals of the FCS playoffs. The Eagles were ranked No. 4 in the preseason FCS poll and third nationally in the coaches' poll.
Eastern Washington has played tough against Pac-12 schools in recent years, falling 30-27 to Washington in the season opener in 2011 and 24-20 to Washington State last season.
"That's a good football team with good players. They've been good for a long time," Riley said.
The Beavers went 9-4 in 2012 and played in the Alamo Bowl. It was the biggest turnaround in school history over the season before which opened with a 29-28 overtime loss to the Hornets.
The Eagles rolled up 625 yards of offense. Eastern Washington scored on every possession except for one in the third quarter when Adams left briefly with cramping.
The Beavers led 7-6 after the first quarter as Eastern Washington's first two scores were a pair of Kevin Miller field goals, but Adams threw a touchdowns to Clark and two to Cupp as the Eagles took a 29-17 lead into halftime.
Oregon State got back on top briefly in the third, with a 7-yard TD reception by Cooks and a 3-yard scoring run for Woods. The 2-point conversion made it 32-29 Beavers.
From there the teams traded scores. Oregon State led 46-43 after a 3-yard TD run by Woods with 4:50 left. However, Adams orchestrated an 11-play, 75-yard drive, which he fitting capped with his final touchdown run.
"We didn't play to our potential today, but we have the guys to do it," Oregon State cornerback Rashaad Reynolds said. "That's not an excuse. We've all played football for a long time."