Galippo is latest to be hurt

USC’s linebacker depth, the envy of college football coaches across the nation, took another hit Wednesday and left the Trojans with several question marks going into Saturday’s Pacific 10 Conference game at Washington.

Freshman Chris Galippo became the latest linebacker relegated to the sideline because of a back problem that could force him to seek a medical redshirt.

Galippo joined junior Brian Cushing (ankle), who will miss the Washington game and possibly more, and freshman Malcolm Smith (hip), who has not practiced this week.

Senior Thomas Williams is expected to start at strong-side linebacker in place of Clay Matthews, who broke his left thumb against Nebraska and injured his right shoulder against Washington State.

Matthews will play against Washington, but the top-ranked Trojans are experimenting with various combinations to offset the dual threat posed by Washington quarterback Jake Locker.

“Basically, everyone is moving around,” middle linebacker Rey Maualuga said.

Cushing said he would try to be ready for the Oct. 6 game against Stanford, but the sprain and bone bruise could take longer to heal.

“I can run around, I can do stuff, but you’ve got to tackle 250-pound guys -- that’s a lot of weight going into it, a lot of force,” Cushing said. “A lot more than I think my ankle is ready for.”

Galippo said an unspecified back problem began in high school. It had dissipated until a flare-up during training camp, then resurfaced this week. Galippo said Wednesday that he was unable to sleep on his back for three nights and that he would meet with doctors to review results of an MRI exam.

“There’s no doubt in my mind I could go the rest of the season,” Galippo said.

Coach Pete Carroll, however, said surgery was “not out of the question.”

“If that’s what it takes, I don’t think it’s too late to get the year back with a medical redshirt,” said Galippo, who has played in all three games.

Last season, fullback Stanley Havili broke his leg in the third game and was granted a medical redshirt by the NCAA.

Despite the injuries, Maualuga, Keith Rivers and the rest of the linebacker corps are preparing to contain Locker, the Huskies’ leading passer and rusher.

“He won’t slide, he’s going to try and run you over,” Maualuga said.

Asked if he preferred that approach from quarterbacks, Maualuga said, “Can’t wait.”

Carroll had players take a knee at the conclusion of practice and then emotionally delivered a rare, extended on-field address.

“I want them to be prepared for the fact that [Washington is] going to do good things in this game and the crowd is going to elevate and they are going to be fired up,” Carroll said. “I was thinking about it: This is a young team. Things have been kind of easy. . . . I just want them to be aware of what’s going to happen and what it’s going to be like so they’re not surprised in any way.”

USC is 2-1 at Husky Stadium under Carroll. In 2001, Washington kicked a field goal as time expired to win, 27-24. USC won, 43-23, in 2003, and 51-24 in 2005.

Cornerback Cary Harris (shoulder) will not play against Washington. Sophomore Shareece Wright will start in his place. . . . Senior center Matt Spanos (triceps) practiced again and said there was a chance he could be cleared to play against Washington.

gary.klein@latimes.com