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After being held to 62 yards rushing against Stanford, Oregon had 10 rushing yards in the first half against Utah before an adjustment led to some open holes for Byron Marshall, who scored two rushing touchdowns.

(Bruce Ely/The Oregonian)

EUGENE -- The numbers have been very unlike Oregon: 62 rushing yards at Stanford. Ten rushing yards in the first half against Utah, and 145 for the game.

But nobody on one of the nation’s best running attacks seems to be worried as the Ducks try to lock down a berth in the Pac-12 Championship game with victories at Arizona and against Oregon State.

“I’m not worried at all,’’ center Hroniss Grasu said. “We are going to get it; we are going to fix it.’’

Before the Stanford game, Oregon was the nation’s second best rushing attack, averaging 331.5 yards per game. Now they are 10th at 285.9 yards per game. There are several factors in play to account for the decline: At the forefront is the two opponents. Stanford has the nation’s fourth best run defense and Utah is among the most physical teams in the Pac-12. The Utes have the Pac-12’s fourth best run defense.

Another factor has been Ducks quarterback Marcus Mariota, who has been hampered by a left knee injury. In the past two games, the Ducks have abandoned one of their most potent attacks -- the spread option -- in order to protect Mariota from being hit. With Mariota out of the equation as a runner, both Stanford and Utah stacked their defense to stop the Ducks’ running backs, daring Mariota to beat them with his arm.

Grasu says that’s fine with him, because they way the Ducks look at it, it creates a pick-your-poison scenario.

“If you want to keep stopping the run, we are going to keep passing the ball,’’ Grasu said. “If you want to defend the passing game, we will run the ball. Whatever they do, we will adjust off it and do whatever it takes to win the game.’’

A key Saturday against Utah was an adjustment offensive line coach Steve Greatwood made at halftime. Utah was sending blitz after blitz at the Ducks, sometimes having the inside linebacker attack from the edge instead of inside. The Ducks changed their blocking schemes to cut off those attacks from the edge, and in the second half, the Ducks rushed for 135 yards on 20 carries, an average of 6.7 yards per carry.

“I knew that early on it would be a bit of a struggle until we figured out their pattern of blitzing against our run,’’ Greatwood said. “And it was a struggle in the first half. But I thought we did a much better job in the second half picking up their pressures, and we hit some decent runs.’’

Starting left tackle Tyler Johnstone said the line wasn’t having trouble with Utah’s physicality. The problem was in communicating to each other.

“They were confusing us a little bit with the stuff they were throwing at us,’’ Johnstone said. “But at halftime we kind of relaxed a little bit and realized this was stuff we had seen in practice.’’

Arizona ranks in the middle of the Pac-12 in stopping the run, allowing an average of 163 yards, and it will be interesting to see how the Ducks gameplan for the Wildcats (6-4 overall, 3-4 Pac-12).

Offensive coordinator Scott Frost said he expects Mariota to be 100 percent healthy by Saturday, perhaps to the point where he doesn’t wear his knee brace. Will that mean a return to the spread option, where Mariota reads whether to keep the handoff in the belly of the running back or pull it and run himself? Or will the Ducks once again rely on the accuracy and decision making of Mariota throwing?

“Ideally, we would like to do both,’’ Frost said.

Still, the Ducks know they shouldn’t have to rely on Mariota and the threat of the spread option to resuscitate their running game. Twice in the first half against Utah, the Ducks were stonewalled on rushes on 3rd-and-2: once De’Anthony Thomas was held to no gain, and another time Mariota was thrown for a six-yard loss before he could handoff.

“I wasn’t very happy with how we ran the ball in the frist half,’’ Frost said.

The Ducks should have at least two all-conference linemen this season: Grasu at center and Tyler Johnstone at left tackle. The rest of the line has been beat up and under some internal scrutiny. Mana Greig lost his starting job at left guard. Jake Fisher temporarily lost his starting job at right tackle. And through it all, true freshman Cameron Hunt has made starts at both tackle and guard in the last four weeks.

Greatwood said the shuffling of starters is not so much an indication that some are playing poorly, but rather an indication that he doesn’t want complacency.

“I’m never going to be one to sit pat,’’ Greatwood. “If I think we can help our performance by making adjustments, then that’s what I’m going to do. We are always trying to improve.’’

With a berth in the Pac-12 title game at stake in the final two games, there is no better time to improve.