Trojans are treading a fine line on offense

It took nearly a month and more than 25 practices, but USC on Monday finally achieved a milestone of sorts when its projected starting offensive line finally practiced together for an extended period.

The line, and how it will react to game conditions, is one of the Trojans’ biggest mysteries heading into Thursday’s opener at Hawaii.

To stave off injuries, USC conducted full-contact tackling drills only once early in training camp. So offensive linemen have not practiced cut blocking or played at full speed.

Coach Lane Kiffin said Monday that the unit would be “a work in progress” and conceded that he was concerned with how the limited-contact approach might affect the line and the running game.

“That’s going to be a big question mark,” he said.

USC has only 12 scholarship offensive linemen on the roster. About half have little or no game experience.

Ideally, USC’s staff wants senior center Kristofer O’Dowd to be flanked on the right by sophomore guard Khaled Holmes and junior tackle Tyron Smith. Senior guard Butch Lewis and sophomore tackle Matt Kalil would start on the left side.

But injuries prevented that group from working together for more than brief periods until Monday.

“It’s just good to get that feeling that everybody’s healthy,” said the 6-foot-5, 280-pound Smith, a starter last season.

O’Dowd had off-season shoulder surgery but appears to be regaining the form that made him a first-team All-Pacific 10 Conference selection two years ago.

Lewis, who plays all positions except center, is rounding into shape after sitting out most of training camp because of a groin injury.

Holmes, a backup in three games last season, remains limited while nursing a neck condition.

Kalil was slowed by minor injuries early in camp but has locked down the spot where he started last December in the Emerald Bowl.

“I feel more prepared than I did last year in that game,” said the 6-7, 295-pound Kalil. “I’m a lot bigger and a lot more confident.”

If the core group remains injury-free, a challenge for every major-college football team, the line presumably would be a strength.

Junior Michael Reardon, who has practiced at every position, will be the utilityman for a unit that on Sunday lost backup center Abe Markowitz, who suffered a broken bone in his foot and will have surgery that will sideline him at least six weeks.

USC’s projected depth took a hit in July when Seantrel Henderson, regarded by some as the nation’s top prospect, asked to be released from his letter of intent and enrolled at Miami.

The Trojans signed only three offensive linemen in the last two recruiting classes, redshirt freshmen Kevin Graf and John Martinez and first-year freshman Giovanni DiPoalo.

Offensive line coach James Cregg said supplementing the position group would be a primary focus as the Trojans move forward.

“It’s the No. 1 need on our football team right now,” he said. “Without a doubt.”

Quick hits

Kiffin said he was leaning toward redshirting freshman receiver Kyle Prater, who has been slowed by injuries through spring practice and training camp…. Senior fullback Stanley Havili, sophomore quarterback Matt Barkley, senior cornerback Shareece Wright and senior linebackers Michael Morgan and Malcolm Smith were elected team captains by teammates.

gary.klein@latimes.com