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LOS ANGELES (AP) Whenever Tre Madden got discouraged while he sat out two of the past three seasons with injuries, his Southern California teammates stepped in with positive thoughts and uplifting wishes.

Now that Madden is healthy again, the tailback is eager to pick up his fellow Trojans in a major way.

Madden is expected to start for eighth-ranked USC at the Coliseum on Saturday night when Arkansas State visits for the season opener. He's hoping the experience finally closes a circle of injury and rehabilitation that has defined the last three years of his life.

''It's tough, and I'm not going to sugar-coat it for my teammates, because they're my brothers,'' Madden said. ''Being positive is the biggest key, and that's hard to do. When you get down, you've got to remember you're on your way back.''

Although he has been outstanding when healthy, Madden has played in just 11 games since 2011, back when he was still a freshman linebacker. Madden made the switch to tailback in early 2012, but a torn knee ligament and a case of turf toe scuttled two full seasons and left some fans wondering if he could ever fulfill his tantalizing promise.

''I had no doubt,'' Madden said. ''I'm confident in my healing process. Mentally, when I got ready after the last surgery, I was on track to be healthy again right away. It was definitely frustrating, but it's in the past. I'm looking forward to being as ready as I can be.''

The Trojans think Madden is ready - and coach Steve Sarkisian is really hoping he stays that way.

Madden is expected to fill much of the void left by tailback Javorius Allen, a 1,000-yard rusher last season. Allen is competing for a backup job with the Baltimore Ravens after leaving USC early for the NFL.

Although Tailback U. is stocked with its usual bounty of young talent at the position, junior Justin Davis is the only other returning scholarship player at the position - and the speedy Davis has struggled with a hamstring injury in camp. The Trojans hope the power-running Madden can be productive and healthy, but the latter is a much bigger question mark than the former.

''It's the same Tre (who) played two or three years ago when he was healthy,'' quarterback Cody Kessler said. ''He's such a powerful running back, but he has kind of everything. He's fast. He can run the ball. He can throw the ball. He can catch the ball. He's an all-around athlete, and that's awesome to have in the backfield.''

Madden's most important trait to Kessler is his veteran aptitude for blocking and blitz pickups, which will be vital with an array of freshmen backups behind Madden and Davis.

''I can always trust him,'' Kessler said.

Madden arrived at USC as a prize recruit from Mission Viejo, California, and Lane Kiffin's staff switched him to offense as a sophomore. The Trojans had ample reason to expect success: Madden's father, Curtis, was a running back at Kansas State, and his maternal grandfather, Lawrence McCutcheon, played running back for the Los Angeles Rams.

But Madden's next season ended before it began when he hurt his left knee without contact during practice, forcing him to sit out all of 2012.

Madden justified his coaches' faith in him with a 703-yard rushing season in 2013, thriving even while missing three games with hamstring injuries. He even had three straight 100-yard games to open the year, becoming the first USC tailback to do that since Heisman Trophy winner Marcus Allen in 1981.

Madden and Javorius Allen were expected to be an imposing duo last year, but Madden never got into a game. His toe injury stubbornly refused to heal, eventually forcing him to give up on the season.

Madden was still limited during spring practice, but has been solid in fall camp. The Trojans hope he'll stay that way.

''He's a really good fit for our offense, for what we're trying to do,'' Sarkisian said. ''We just want him to stay healthy, and we're going to do everything we can to make it happen.''