There are lingering questions about how much his knee injury contributed to the Ducks' 26-20 loss at Stanford last Thursday. Oregon (8-1, 5-1 Pac-12) doesn't discuss injuries, and Mariota hasn't been specific about what's going on despite a school official acknowledging to Ivan Maisel of ESPN.com that he had a partial sprain of his MCL prior to that game.
Asked this week whether his knee is an issue, Mariota replied: "Not at all." Pressed whether he is 100 percent, he said: "That's something that I can't tell you."
It became apparent that Mariota's mobility was hampered against Stanford as he wore a brace. His Heisman Trophy candidacy took a hit after passing for 250 yards and two touchdowns but rushing for minus-16 yards after being sacked three times.
"My knee is what it is," Mariota said after Tuesday's practice, where he again wore the brace. "I'm not going to use that as an excuse."
Mariota, a sophomore, has completed 63.3 percent of his passes for 22 touchdowns and hasn't thrown an interception in 327 attempts dating to last season -- an ongoing Pac-12 record. He's also rushed for 495 yards and nine TDs.
The loss to Stanford dropped Oregon from No. 3 to No. 6 in the BCS standings, and the Ducks will need to win their remaining games and hope the Cardinal drop one of their final two conference contests to get back in control of hosting the Pac-12 championship game.
The Associated Press contributed to this report.