Tailback Stafon Johnson started and finished last season near the bottom of USC's depth chart.
By the time the top-ranked Trojans play Idaho next week, the sophomore could be sitting atop it.
A shoulder sprain is expected to keep fifth-year senior Chauncey Washington on the Coliseum sideline for the Sept. 1 opener. Washington said before Thursday's practice that he would possibly be out two weeks.
But after watching the Trojans' one-hour workout with his right arm in a sling, Washington said, "I'm thinking a week. I'm day to day."
Of missing the opener, he said, "I won't believe it till it happens."
Nevertheless, with sophomore C.J. Gable still nursing a groin strain, and sophomore Allen Bradford not practicing Thursday to rest a sore hip and groin, Johnson and senior Desmond Reed are perhaps the only fully healthy tailbacks.
Johnson, the former Dorsey High star, impressed throughout training camp and rushed the ball well during the Trojans' final scrimmage on Wednesday at the Coliseum.
"I feel as if all of us are confident to actually start because of the preparation that they put us through," Johnson said Thursday. "But whatever happens, happens. And whatever happens, you have to be ready for it."
Johnson is not dwelling on last season's disappointment, when his attitude and work habits put him on the scout team.
"Whatever happened last year, I really kind of put it behind me. . . . I'm trying to look forward and steadily progress," he said.
Reed began training camp regarded mainly as a punt-return specialist. But he is also prepared for a large role in the backfield.
"I'm definitely ready for a big bang to end my career here at USC," he said. "I know the playbook like the back of my hand."
Bradford ran well against the first-team defense Wednesday, but the discomfort from an awkward fall during training camp lingers. Like Johnson and Reed, he said he would be ready for a possible starting role against Idaho.
"I'll let the cards play out, however they're dealt," he said. "Whatever situation happens, I have to step up and take over."
Coach Pete Carroll said Gable could have participated in the scrimmage but was held out as a precautionary measure. Gable started last season's opener against Arkansas and the last four games.
"We know what he can do and we love the way he plays," Carroll said. "Regardless of how Chauncey comes out, we've got a pretty good feel for how we would go, and all of those guys deserve to play."
Freshman Broderick Green is physically sound, but he was held out again because of eligibility issues. Carroll said USC would find out today whether the NCAA Clearinghouse has certified Green.
Freshman Joe McKnight, who has not practiced since Aug. 15 because of a stretched knee ligament, would have to return by Monday to have a chance to play in the opener, Carroll said.
According to USC coaches, quarterback John David Booty has not had a pass intercepted since training camp began nearly three weeks ago.
"I'm just seeing the field clearly and not trying to force the issue," Booty said. "I ran into that sometimes last year where I might have tried to stick something in where, looking back on it, you know maybe I shouldn't have done that.
"All those things I've been going over in the off-season and trying to hit home in my head, they're all starting to pay off."
Offensive tackles Sam Baker (rib) and Charles Brown (back spasms) and linebacker Keith Rivers (groin) were among those who did not practice. . . . The Trojans practice today and Saturday but are scheduled to have Sunday off.