SANTA CLARA, Calif. -- The San Francisco 49ers began training camp Thursday with running back being a crowded position.
It is suddenly thin after two early injuries.
Running back/returner LaMichael James dislocated his left elbow, a league source confirmed. He is expected to miss about a month, meaning he will likely miss the entire preseason.
Barring a setback, he should be ready to play Week 1 at the Dallas Cowboys.
James, a 2012 second-round pick out of Oregon, was considered a bubble player when camp started. But valuable backup running back Kendall Hunter tore his ACL on Friday and is out for the season. James is expected to take Hunter's place.
Prior to James' injury, 49ers coach Jim Harbaugh was high on the young running back.
"As far as LaMichael James, we have complete and total confidence in LaMichael James, and I don't see anything in terms of stepping up or proving anything on his part," Harbaugh said Sunday. "We know him to be a very fine football player. I think if you look at where he was at last year at this time in training camp, he got an MCL injury that kept him out of action for quite a while and affected where he was on the depth chart. And then, eventually, he got his chance.
"But he was right in this same mix last year at this time. He's on familiar ground. He knows the team has always counted on him to be a top football player at the highest level."
James was hurt on a blitz pick-up drill and was carted off the field. He dislocated his right elbow in college in 2011 and missed 23 days. James has battled nagging injuries since joining the 49ers. In addition to his backup running back duties, James was expected to battle rookie receiver Bruce Ellington for return duties.
With Hunter done for the season and James out for the preseason, the 49ers are thin at running back. Starter Frank Gore, 31, likely won't play in the preseason.
Second-round pick Carlos Hyde and practice-squad member Jewel Hampton have both looked good.
Harbaugh said Friday he believes the reason running back Marcus Lattimore isn't practicing yet is more due to the physical side and not the mental side of his recovery from a horrific 2012 knee injury while playing at South Carolina. Saturday, 49ers GM Trent Baalke said both were factors.
"There's a [physical] percentage it needs to get better. As I've watched this offseason, it's got better daily," Harbaugh said Sunday. "Not 100 percent yet."
The team is hopeful Lattimore, a fourth-round pick last year, will practice soon.