Washington Redskins Coach Mike Shanahan says he hasn’t decided whether he wants to enter the regular season with a primary ball carrier or a tailback-by-committee approach.

“I really don’t know how to answer it because you don’t know until guys get in game situations, with running backs,” Shanahan said after Thursday’s opening practice of training camp at Redskins Park. “Sometimes you get a running back that can carry the load by himself. Most of the time you kind of have two or three guys. But we’ll just have to wait and see as the preseason goes on, who wins the playing time.”

Tim Hightower, Roy Helu and Evan Royster are competing for playing time at the position. Hightower is returning from a torn anterior cruciate ligament in his left knee suffered last October. Helu and Royster ran well after Hightower’s injury, and Shanahan declined to name Hightower or anyone else the early front-runner for the starting job.

“Last year he [Hightower] was a first-teamer,” Shanahan said. “But obviously Roy did a good job. Royster did a good job. We’ve got a lot of guys that I believe have the ability to play and play well. So we’ll just let it play out.”

Hightower’s training camp workload will be watched closely as he returns from his injury. Shanahan said he made that clear to Hightower when he told him to make certain he doesn’t suffer a setback in preparing for the regular season.

“I said, ‘Any time you have an ACL tear, especially as a running back, your tendency is [to say] hey, I feel good.’ And I said, ‘Just don’t over-do it. Just take a few reps here and there. Go through your drill work,’ ” Shanahan said. “Tim is one of those guys that doesn’t want to give up a rep. You know, I think he’s smart enough to know that he’s got to be ready by the first regular season game, not by the first preseason game.”

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