EUGENE, Ore. >> Marcus Mariota takes a lot of ribbing over his course load this semester: yoga and golf.

For those joking that Mariota need only add underwater basketweaving, the reality is that the quarterback for No. 3 Oregon finished his degree requirements in just three years.

Oh, and opponents should also take note that those easy A’s mean Mariota is going to be able to spend a lot more time focusing on football this season.

“With the amount of free time I’ll have, it will mean being early in the treatment room, remaining healthy and doing recovery stuff, and along with that film work and being around the building more to do that kind of thing. To be able to have a little more time for football it will really be beneficial to me,” he said.

The Ducks open at home on Saturday night against South Dakota.

Mariota averaged nearly 282 yards passing per game and threw for 31 touchdowns with only four interceptions last season. He also rushed for 715 yards and nine scores. His 4,380 yards of total offense set a school record.

All the while he was also taking 20 units. Toward a science degree, no less. He graduates (early) in December.

“He was taking all these upper division biology, upper division science. He had 20 credits and aiming to get done in time to graduate. It was just impressive. He’s managed his media obligations and still doing everything he has in the community, which is substantial by anyone’s measure,” coach Mark Helfrich said.

There was speculation last season that he’d jump at opportunities in the NFL, but Mariota announced early on that he was sticking with the Ducks.

Mariota, a redshirt junior, said his decision didn’t have all that much to do with “unfinished business” after Oregon lost two games last season to fall out of national championship contention. It had more to do with finishing school and the Ducks. He said he’s interested — someday — in pursuing a career in sports medicine.

“For me I wanted to come back and get my degree, come back and enjoy another year with the guys and experience college for another year,” he said.

In large part because of Mariota’s return, the Ducks enter the season at No. 3 in the AP Top 25. Oregon has been picked in the annual poll of reporters who cover the conference to finish this season atop the Pac-12 North and claim the league’s championship.

Mariota has never led the Ducks to the Pac-12 title; Darron Thomas was the quarterback when Oregon won in 2011.

Mariota was a Heisman contender last season before struggling with a left knee injury. The Ducks had climbed to No. 2 in the AP rankings but Mariota tore the medial collateral ligament in his left knee against UCLA and the next week Oregon fell to Stanford 26-20.

The Ducks also lost 42-16 to Arizona in Tucson, dropping Oregon to No. 12 and out of the running for a national championship bid.

The Cardinal went on to claim the Pac-12 North and beat Arizona State in the league championship to earn a spot in the Rose Bowl. Oregon wrapped up the season ranked No. 10 at 11-2 after defeating Texas 30-7 in the Alamo Bowl.

“Too many times we were relying on Marcus, especially in the Arizona game or Stanford. We were relying on Marcus to make big plays and that shouldn’t ever happen again,” center Hroniss Grasu said when Oregon opened fall camp. “A lot of that comes down on the offensive line. We just gotta take the slack off his shoulders.”

The Ducks’ primary concern at the position this season is who will be Mariota’s backup.

Sophomore Jeff Lockie appeared most likely to earn the job, but Oregon’s practices are closed so it’s uncertain if anyone else has emerged during fall camp. Lockie came off the bench in nine games last season, completing eight of 13 passes with an interception and no touchdowns.

Jake Rodrigues and Damion Hobbs transferred, so the team has Taylor Alie and promising incoming freshman Morgan Mahalak competing for second-team reps with Lockie.

Backups aside, Helfrich said Mariota’s decision to return for the season made a major statement for the entire team.

“If I’m the backup guard and I see that guy forgo what he could have made, it’s not some lip service dream, this is a reality of a ton of money. It’s like, ‘That guy turned down how much? OK, I’ll watch him.’ That’s huge,” Helfrich said. “I think it speaks to the type of guy he is, the type of team we are, and certainly, hopefully, to the type of program that we have.”