SANTA CLARA – There will be at least one lineup change Thursday when the 49ers close the preseason against San Diego.

Coach Jim Harbaugh said Tuesday that Jonathan Goodwin will start at center instead of Adam Snyder, who started the first three exhibition games. Goodwin and Snyder have been platooning on the first-team offensive line.

"Like I said before, I really do believe we have seven starters on our offensive line," Harbaugh said. "We're going to look at combinations, find out what the best one is as we move forward."

Goodwin said he hasn't been told directly he'll start, but he acknowledged he has been working with the first group more this week than he has in recent weeks.

At cornerback, Tarell Brown is in line to start his second consecutive game. Fellow cornerback Shawntae Spencer (hamstring) said he doesn't expect to play Thursday. That likely means Brown will start the regular-season opener Sept. 11 against Seattle.

Cuts begin – The 49ers reduced their roster to 80 players by cutting seven, including linebacker Scott McKillop, a 2009 fifth-round pick who suffered a severe knee injury last year in training camp.

The 49ers must further trim their rosters to 53 players by Saturday.

"I think for Scott, it was a decision that was made now so that there could be a chance to get on with another football team," Harbaugh said. "The way that it has shaken out, he wouldn't have a spot here on our team. So especially when it comes to guys that have been on the 49ers, and have been 49ers, you go a little extra to try to make it the best possible situation for them."

Also released were wide receivers Kevin Jurovich and Tyler Beiler, guards Donovan Edwards and Nick Howell, running back Seth Smith and kicker Sam Paulescu.

More Crabtree – The 49ers removed wide receiver Michael Crabtree from the physically unable to perform list Tuesday, and for the second consecutive day, he was active at the start of practice. Crabtree (foot) was still on the PUP list when he practiced briefly with the quarterbacks Monday.

Harbaugh, however, bristled at the suggestion the team had bent the rules.

"There's absolutely no malice by the team to try to break any rules or steal practice reps for Michael Crabtree," he said. "I mean, did he or did he not practice? I can answer that question: He did not practice. That was obvious. I mean, reports that he ran five-yard routes. He didn't run any routes. He was walking around. He played catch."

Crabtree's activity Tuesday was similar to what it was Monday. He ran a few steps before turning around and catching passes from each of the team's quarterbacks. Crabtree hasn't been medically cleared for a full practice and is unlikely to play Thursday.

Et cetera – Wide receiver Braylon Edwards said he still doesn't know if he will be suspended for a DUI incident that happened last season. The league said the case is still under review.

"Everybody asks me the question," he said. "I don't know. I don't know what's going on. It's pretty much on the league. I'd prefer if people don't ask me that question because I don't know."

• Crabtree (foot), Spencer (hamstring) and safety Reggie Smith (knee) have been rehabilitating on a side field during the main part of practice.

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