CORVALLIS - Today’s game between Stanford and Oregon State is likely to be affected by players who aren’t on the field as much as those who are.

Both teams are depleted by injuries and other issues.

Oregon State (4-3, 2-2 Pacific-10) lost starting left tackle Tavita Thompson this week when he was ruled ineligible by the NCAA. The Beavers didn’t give details, citing privacy issues.

The Beavers’ offensive line already lost left guard Jeremy Perry Aug. 30 to a broken bone in his leg. Now, right guard Roy Schuening is battling pneumonia, and right tackle Andy Levitre hurt his leg in practice, although it did not appear serious.

Ryan Pohl, a 6-3, 278-pound redshirt freshman, will replace Thompson. If Schuening can’t play, sophomore Gregg Peat, redshirt freshman Mau Nomani or junior Marcus Henderson could play against the Cardinal (3-4, 2-3).

Oregon State, coming off a bye after beating California 31-28 in Berkeley, will also likely be without starting cornerback Keenan Lewis for another week because of a knee injury.

The Beavers earlier lost receiver and punt returner Sammie Stroughter for the season with a kidney injury. Defensive back Coye Francies was dismissed from the team just before fall camp, and punter Kyle Loomis quit.

Stanford is especially thin at running back. Coach Jim Harbaugh said earlier this week that Jason Evans would miss the rest of the season with an injured left knee.

Evans tore his ACL in last Saturday’s 21-20 victory at Arizona and was expected to have surgery next week.

Evans was playing in place of injured starter Anthony Kimble, who is nursing a sore shoulder. Freshman Jeremy Stewart also has an injured shoulder.

Toby Gerhart could play this week after missing the past five games with a knee injury, but it’s likely redshirt freshman Tyrone McGraw will start against the Beavers after running for 50 yards on 16 carries last week.

Harbaugh also said offensive lineman Allen Smith will not return this season from his left knee injury. Smith was hurt in the Sept 22 game against Oregon.

Earlier, Stanford lost linebacker Fred Campbell for the season because of fractured vertebrae in his neck. Starting quarterback T.C. Ostrander had a seizure in a Palo Alto restaurant, and Tavita Pritchard has since taken over.

Pritchard led Stanford to their upset victory over USC back on Oct. 6, his first college start. With the sophomore quarterback, the Cardinal have won two its their last three.

“He’s definitely an athlete,” Oregon State defensive end Slade Norris said. “Anytime that pocket is pressured he’s out there making plays. It will kind of be like a Rudy Carpenter (of Arizona State) all over again, but obviously we’ll have to defend better this time. We have experience facing mobile quarterbacks. It will be a challenge, but we definitely can do it.”

Oregon State has seen growing improvement from starter Sean Canfield, who has thrown for seven touchdowns and 13 interceptions.

But he didn’t throw an interception in a pressure-packed game against Cal and his 18-of-33 passing for 186 yards.