The 49ers went through training-camp practice No. 7 without some major members of their defense - Patrick Willis, NaVorro Bowman, Aldon Smith and Chris Culliver, who appeared to suffer a serious left knee injury while covering a punt early in the session.
With Willis and Bowman out, the first-team inside linebackers were Michael Wilhoite and Nate Stupar, although good-looking draft pick Nick Moody got a chance to work alongside Wilhoite with the first-stringers later in practice. Wilhoite played Willis' "Jack" linebacker position early; Moody moved to "Jack" late. Which is to say, Wilhoite can play either of the inside-linebacker roles.
Meanwhile, Tramaine Brock assumed the role of the No. 3 cornerback during practice. That's a little surprising given the fact that Nnamdi Asomugha has been playing well, especially on Wednesday when he had an interception and a pass break-up on an attempt to Anquan Boldin. Asomugha had another strong session today as well - he knocked away a pass to Chad Hall - and he got recognition from Jim Harbaugh after practice.
"Yeah, he did have noticeable, eye-popping plays, yesterday especially," Harbaugh said. "He's been good. I think he's got a good grasp of what we're doing defensively. In shape, doing a nice job."
Asomugha and Perrish Cox were the second-string cornerbacks. Cox intercepted Colt McCoy early in the session. He also is the No. 2 nickel cornerback and was one of four players - LaMichael James, B.J. Daniels and Hall were the others - who returned punts. In fact, Cox was the punt returner when Culliver got hurt.
Bowman's and Aldon's Smith's injuries don't appear serious. They were working out on a side field during the start of practice. Harbaugh also said he didn't think Willis' fractured right hand would keep him out of any regular-season games. Culliver was getting an MRI at the end of practice. His injury appears to be the most serious.
Vic Fangio is a man of his word. The team's defensive coordinator said that four different safeties would get a chance to win the starting free-safety role this year. And all four of those players have gotten a chance to play opposite Donte Whitner with the first unit so far. Today, Trenton Robinson was with the first string early in practice while first-round pick Eric Reid got a chance late. Craig Dahl began camp as the de facto starter but gave way to C.J. Spillman earlier this week.
Receiver Quinton Patton caught a pass in team drills. The fourth-round pick is dealing with a broken finger on his left hand, and he's been instructed not to catch the ball with that hand. So he made a catch solely with his right hand on a throw from Scott Tolzien.
With so many injuries at wide receiver, Daniels has been used at wideout (in addition to quarterback, tailback and punt returner). He did all four today and looked very good in going up to catch a pass from Tolzien in the back of the end zone. Alas, the official nearby ruled that one of Daniels' feet came down out of bounds. Daniels also saw time at slot receiver during today's session.
Said Harbaugh of the rookie: "t's been impressive how he goes from receiver to quarterback and then takes off and puts on the gloves and he's back at running back. He's doing a pretty darn good job. I think just what we have been doing is more and more quarterback play as the days go by and he's showing a good grasp of the offense. Arrow up there."
During 7-on-7 drills in the red zone - one of the scenarios the 49ers have concentrated on in training camp - Colin Kaepernick hit tight ends Vance McDonald and Garrett Celek on back-to-back plays. The play to Celek was particular impressive because Kaepernick was on the run and threaded his pass through traffic to the big tight end.
Anthony Dixon, who plays both tailback and fullback, had a huge block on Moody from the fullback position during a running play. ... On the other side of the ball, safety Michael Thomas, who is the No. 3 nickel corner, stuck Jewel Hampton at the line of scrimmage on a running play.
Seventh-round pick Carter Bykowski was back at practice after leaving yesterday's session.
-- Matt Barrows