EUGENE, Ore. >> Trailing Michigan State 27-18 in the third quarter and facing a third-and-10, Oregon quarterback Marcus Mariota found himself confronting a decision while on the run: pitch the ball to freshman Royce Freeman, or try a keeper.

Mariota, who is as adept with his feet as he is with his arm, decided on the flip to Freeman for the first down, and the No. 3 Ducks would go on to score the first of four unanswered touchdowns for a 46-27 victory Saturday night over the No. 7 Spartans.

Afterward, many of the Ducks — and even the Spartans — pointed to that play as the pivotal moment of the game, which was billed as the premier nonconference matchup of the season.

"I was looking for him to run it," said a surprised Freeman, who had a pair of rushing touchdowns in the victory. "I was going to block for him."

Mariota finished with 318 yards passing and three touchdowns, solidifying his position as an early Heisman favorite. He now has 69 touchdown passes for his career, an Oregon record.

Redshirt freshman Devon Allen had three catches for 110 yards and two touchdowns for the Ducks.

The loss snapped an 11-game winning streak for the defending Big Ten- and Rose Bowl-champion Spartans, who went 13-1 last season. Connor Cook threw for 343 yards, two touchdowns and two interceptions.

"I just tried to keep a calm mind-set. I tried not to get caught up in the game, caught up in the moment at all," Cook said. "They just made more plays than us. We had some opportunities on offense and I needed to grasp them and I didn’t."

The Spartans had the second-ranked defense in the nation last year, allowing opponents an average of just over 252 yards per game. But the high-flying Oregon offense — combined with temperatures approaching 100 degrees — appeared to wear on Michigan State as the game went on.

The two teams both went three-and-out on their opening series and it appeared that defenses would rule the day. The Spartans reached Oregon territory midway through the quarter, but on third-and-10 on the 38, Erick Dargan intercepted Cook and ran it back 36 yards.

The Ducks capped the drive when Thomas Tyner barreled over the goal line for a 1-yard touchdown, and Oregon added the conversion for an 8-0 lead.

Matt Wogan’s 28-yard field goal pushed the Ducks’ lead to 11-0. But Michigan State answered with an impressive drive topped by Jeremy Langford’s 16-yard scoring dash.

Mariota hit Allen with a 70-yard touchdown pass to give the Ducks an 18-7 lead with 10:12 to go in the half. Allen, the NCAA’s reigning 110-meter hurdles champion, shook off strong safety RJ Williamson before sprinting in for the score.

The scoring pushed Mariota past Darron Thomas (66) on Oregon’s all-time list. Mariota has thrown at least one touchdown in each of the 28 games he’s played at Oregon.

Michael Geiger kicked a 34-yard field goal and Cook added a 7-yard touchdown pass to Tony Lippett with 2:26 left before the break to pull the Spartans within a point. Michigan State took a 24-18 lead with 18 seconds to go when Josiah Price leaped to grab Cook’s 7-yard TD pass into the end zone.

The Ducks were hurt early in the first half when junior offensive lineman Andre Yruretagoyena was carted off the field with what appeared to be a right leg injury.

Michigan State padded its lead with Geiger’s 42-year-old field goal, but Mariota found Allen with another touchdown pass, this time from 24 yards out, to cut the Spartans’ lead to 27-25.

It was earlier in that series that Mariota made the momentum-changing pitch to Freeman for 17 yards.

"Once I saw Royce 5, 10 yards down the field, I just thought he could get there faster than I could," Mariota said.

Even Michigan State coach Mark Dantonio pointed to the play as the moment the game shifted.

"We had to stop the momentum and we had him dead to right and he got out. We had him. I even said, ‘He’s sacked.’ " Dantonio said. "But again, you have to credit him, that’s why he’s the player he is."