The first question a reporter asked Colorado head coach Mike MacIntyre at his Tuesday press conference: “How is Addison doing?”

That would be Addison Gillam, the Buffaloes’ stalwart sophomore middle linebacker, who in Colorado’s last game was concussed for the second time in three weeks. The Buffs need him more than ever against the No. 22 USC Trojans this weekend, but they can’t depend on Gillam as a player until he is healthy as a person.

Colorado’s bye week got him healthy enough, MacIntyre answered, so Gillam will take the field Saturday with a gimpy elbow and a fast-growing history of concussions to face the irresistible force that is Javorious “Buck” Allen and the Trojan rushing attack.

The junior is USC’s best running back since Reggie Bush, but he plays more like Bush’s former backfield mate LenDale White. Allen is strong, powerful and physical. At 6-foot-1 and 225 pounds, he is as big as some of Colorado’s linebackers.

Allen leads the Pac-12 in rushing yards, and his 135 carries and 781 yards already equal his production from last season. He will test the Buffs’ tackling skills more than any back they have yet faced.

“Tackling well has to be muscle memory,” said CU sophomore linebacker Kenneth Olugbode.

Olugbode and MacIntyre both say forcing fumbles was the team’s biggest defensive focus in practice this week. Ripping the ball out of Allen’s hands might be the only way Colorado’s permeable rushing defense can stop him. Even if it can, USC has a capable backup, sophomore Justin Davis, and a quarterback who rarely makes mistakes.

Junior Cody Kessler wrested the starting job from Max Wittek during the Trojans’ chaotic 2013 season. Kessler was unspectacular that year, but he won. Now, he is the model of efficiency, completing nearly 70 percent of his passes and throwing just a single interception.

But USC hasn’t been winning with offense this season. In its best games — wins over then-No. 13 Stanford and then-No. 10 Arizona and a demolition of Oregon State — its defensive line dominated the line of scrimmage and its corners played suffocating man coverage.

The Trojans will stick with those man looks on the outside, even against Colorado’s star receiver, Nelson Spruce. The junior struggled against press coverage in the Buffs’ loss to Oregon State, and USC, which has a better secondary than the Beavers, doubtlessly thinks they can exploit that.

Despite his quiet game against Oregon State, though, Spruce still leads the nation in receptions and receiving touchdowns and is fifth in yardage. More concerning than Spruce getting open is sophomore quarterback Sefo Liufau having time to deliver him the ball.

There aren’t many more ways to say how bad Colorado’s offensive line has been this year, and this won’t be the game where they bounce back. USC’s defensive line might be the best the Buffs will play all year. They should easily pressure Liufau with a four-man rush.

Sophomore running back Michael Adkins could take some of the pressure off Liufau if he builds on his impressive performance against Oregon State — he more than doubled his rushing total for the season in that game and scored his first touchdown. More importantly, he rarely went down on first contact.

It is better late than never for Adkins to become the consistent running threat that he was supposed to be, that Colorado has lacked all season. The Buffs will also be bolstered by the return of junior running back Christian Powell, who missed the Oregon State game with a concussion.

That won’t push Colorado to victory, though. USC’s strengths — its defensive front seven and its running game — match up against the Buffs’ greatest weaknesses. Colorado has the skill position players to compete with the best defense in the Pac-12 outside of Palo Alto, but its lines will be its undoing.

But crazier things than Colorado upsetting USC have already happened in this unprecedented college football season. We will have a better idea when Buck Allen bursts through the line of scrimmage and Addison Gillam, the Buffs’ battered bastion, is there to meet him.

Contact CU Independent Staff Writer Tommy Wood at Thomas.C.Wood@colorado.edu.