LOS ANGELES (AP) -- Whenever Matt Barkley thought about his final run down the Coliseum tunnel, the Southern California quarterback never imagined doing it with no helmet, no pads - and his throwing arm in a sling.
Instead of facing Notre Dame for a shot at a national championship, the Trojans' star quarterback is sidelined with a sprained shoulder. Instead of playing for the nation's No. 1 team, Barkley's unranked teammates are playing against it.
If this is his storybook ending, Barkley would like to fire the author.
Yet a month of disappointment and discouragement culminating in an injured shoulder still isn't enough to shake Barkley's faith in his decision to return for one more season in the only uniform he ever dreamed of wearing.
"I took a chance," Barkley said Tuesday while a black sling supported his arm. "I don't think enough guys really go for it enough these days, and I did."
Barkley will watch the Trojans' regular-season finale Saturday from the sideline after getting hurt on a sack in last week in USC's loss to UCLA. He doesn't know whether he'll recover in time to play in the Trojans' bowl game, although coach Lane Kiffin is optimistic.
Optimism still isn't difficult to find at USC, even after three losses in four games - and that's mostly due to Barkley's leadership. The Trojans (7-4, 5-4 Pac-12) plummeted out of the Top 25 after starting the season at No. 1, yet the furor over their performance is mostly confined to their fans and college football pundits.
Barkley and the Trojans thought they had a shot at the Heisman Trophy and the national title. They'll get neither, yet they're still having fun.
"It didn't turn out the way I planned," Barkley said. "But I think over these last four years, and especially this year, I've learned so much. (I've) grown, matured a lot since last year I really think, and that will prepare me for the next level and for later in life. I don't regret it one bit."
With the perspective of time, Barkley knows he'll feel even better about his achievements during his four seasons at USC. He rewrote the conference record book during a USC-record 47 starts over four seasons, becoming the Pac-12's leader in touchdown passes, yards passing, completions and total offense.
And Barkley looms as an important leader in USC's history, representing his teammates as their spokesman when the program was leveled by NCAA sanctions in 2010. He never wavered in his commitment during a two-year bowl ban, standing up for the school that first captured his imagination as a kid growing up in Orange County.
"I can't feel worse for a family and for a kid," Kiffin said. "The fact that he's not running down that tunnel in his last game, and now two times in a row he doesn't get to play Notre Dame, it's very unfortunate. We feel as bad as we can, but he'll be stronger for it. He'll come out of this thing, and we're going to go out and play great for him."
Kiffin had lobbied Barkley to stay at USC for his senior year since shortly after he took the job in 2010, and the former Oakland Raiders coach has consciously attempted to prepare Barkley for the NFL throughout his final two seasons. Kiffin is taking it a step further this week: While redshirt freshman Max Wittek studies defenses in preparation for his first career start, Barkley is attending game-planning meetings with Kiffin's coaching staff.
"Matt has been in some of our coaching meetings as far as preparation, how we break down the defense as coordinators and the different personnel, and how we attack everything," Kiffin said. "(We) just thought that would be good for him in a time that there's not much for him to do, to help prepare him on how to prepare for the next level."
Wittek and fellow freshman backup Cody Kessler have praised Barkley's generosity and instruction. The senior plans to be in Wittek's ear on the sideline with encouragement and instruction while facing the Irish's imposing defense.
Barkley should know soon whether he can play in his first postseason game since the 2009 Emerald Bowl in San Francisco. He's more focused on trying to finish a low season on a high note, even if he has to celebrate on the sideline.
"We're in a hungry mood right now to get a win, and I think it'll send us into December feeling great," Barkley said. "Nothing is always as it's supposed to be in life. Sometimes things go as planned, but a lot of the times, things go unaccording to plan. So it's just something you have to deal with, and I'll handle it and stay positive."