SANTA CLARA Greg Roman, the 49ers' offensive coordinator, is looking forward to a Sunday preseason matchup that will pit his offensive line against one of the top pass rushers from 2011, Denver Broncos linebacker Von Miller.
Miller finished last season with 11 1/2 sacks and was named the Defensive Rookie of the Year. And teammate Elvis Dumervil, another undersized but quick pass rusher, had 9 1/2 sacks last season and 17 sacks in 2010.
"They're really good, productive players," Roman said Wednesday. " They can run that hoop pretty well and trim the fat on the edge good. With the crowd noise behind them it will be great work for us. We've got to be on our A game."
The battle between Miller and 49ers right tackle Anthony Davis will be particularly interesting. At 323 pounds, Davis has a decisive edge on Miller (237 pounds) in run blocking. But Davis has struggled against quick outside pass rushers, allowing 9 1/2 sacks last year, according to STATS LLC.
"I think everybody in the NFL is pretty quick," Davis said. "But I know what you mean. He's exceptionally quick."
Quarterback Alex Smith was sacked twice in the first quarter in Saturday's 20-9 preseason loss in Houston, and he was hit five times. But Smith on Wednesday said only one of those hits when left guard Mike Iupati was beaten was because of a pass-protection breakdown.
"Other than that, the protection's been great," said Smith, who called the other hits "self-inflicted."
Wounded knee Cornerback Chris Culliver, who injured his right knee Saturday, said he will not play against Denver.
Culliver said the injury won't keep him out long term, but he has missed all three practices this week.
Culliver is the No. 3 cornerback, entering games when opponents send in three wide receivers. He played 41 percent of the 49ers' defensive snaps last season.
His absence Sunday ought to shed some light on one of the 49ers' better training-camp battles, between backup cornerbacks Tramaine Brock and Perrish Cox.
Brock was the No. 4 cornerback last season, but he struggled Saturday against Houston. Cox, meanwhile, has had an impressive offseason and had an interception against the Minnesota Vikings in the preseason opener.
Running back praised Anthony Dixon's spot on the 49ers' final roster is tenuous, but he got a nice dose of praise from Roman. Dixon entered Saturday's game in Houston after Brandon Jacobs went down because of a knee injury.
He converted a fourth and one early in the second quarter but failed on another. Roman said there was little room to maneuver on both, and that Dixon did well under the circumstance.
"I thought Anthony Dixon had one of his better games since I've been here," Roman said.
Injuries Linebackers NaVorro Bowman, Cam Johnson (knee) and Kourtnei Brown (hamstring) were not on hand for the start of practice. Johnson and Brown were working on a side field with the strength and conditioning staff.
The reason for Bowman's absence is unknown. He was seen walking without a limp in the locker room before practice.