Penn State's offensive line is hobbling less than two weeks into training camp.

Coach Bill O'Brien didn't reveal a full injury report during a conference call with reporters today, but he admitted there are some injuries on the offensive line.

One of those injuries is at left tackle, where redshirt freshman Donovan Smith has been slowed by a hamstring problem. Junior Adam Gress, the projected starter at right tackle, and senior Mike Farrell are working in Smith's place.

"Mike Farrell has had a good camp and he's going to play for us this year," O'Brien said. "Donovan hasn't really practiced a whole lot yet. Hopefully he will get back out there today and (Friday)."

The Nittany Lions are also thin at left guard because of Mark Arcidiacono's foot injury. Arcidiacono entered the summer competing with Miles Dieffenbach for the starting job.

The injury means Dieffenbach will start the Sept. 1 opener against Ohio University.

"Arcidiacono is a kid I feel bad for," O'Brien said. "He's a really great kid who has been injured and he's one of those guys that has been on the shelf a little bit. I feel terrible for him. He hasn't been able to get on the field, and Dieffenbach has basically solidified that starting spot."

O'Brien also said that senior Jake Fagnano is still nursing a hamstring injury. Fagnano entered the summer as the first-team strong safety.

Bill Belton impressing coach

Eliminate tailback from the list of unsettled positions.

O'Brien said sophomore Bill Belton, a wide receiver last season, has "definitely cemented" himself as the starter for the opener.

"Other guys will play," O'Brien said, "but Billy will start the game. He has had a good camp."

Guy Cipriano can be reached at 231-4643. Follow him on Twitter @cdtguy