The highly regarded rookie wasn't in pads, his left leg was wrapped, and he didn't participate in practice at all Tuesday.
It could be the result of going full-bore the past two weeks on a knee that was surgically repaired this spring. That's one of the reasons Richardson didn't fully participate in the NFL Scouting Combine in February.
"It was a little scope," Richardson said at the time of what was termed minor surgery. "I don't even call it a setback."
"I'm always concerned about injuries," Shurmur said. "He's been practicing well. We'll just have to see where he is."
Richardson has been quite impressive in training camp, displaying quickness and toughness. He did miss practice time last week with what Shurmur said was a headache.
Richardson, starting tight end Ben Watson and a few other players limited by various ailments rode stationary bicycles as the team went through regular drills Tuesday.
If Richardson can't play, Montario Hardesty will have the chance to show if he has progressed. A second-round draft pick from Tennessee in 2010, Hardesty tore up his left knee during the preseason that year and missed the entire season. In sporadic time a year ago, he rushed for 266 yards in 10 games.
Copyright 2012 by The Associated Press