SANTA CLARA -- Left tackle Joe Staley, removed from Sunday's game due to a concussion, has yet to receive medical clearance to play in the 49ers' game Thursday night against the Seattle Seahawks.Staley said he is symptom-free and he hopes to play in the 49ers' first game this season against an NFC West opponent."It's really out of my hands," Staley said Tuesday. "It's up to the doctors. Of course, if it was up to me, I'd play. I would've played yesterday."Staley sustained the concussion in the third quarter when New York Giants safety Stevie Brown leveled him with a block as Staley pursued safety Antrel Rolle after an interception.When asked if the block was clean, Staley answered, "Yeah, I just didn't see it. It was one of those deals where I was tracking the ballcarrier, and the guy got a good shot on me. It came out of the blue."Staley sustained a concussion last December against the Arizona Cardinals. He received clearance seven days later, the day before the 49ers played the Pittsburgh Steelers in a Monday night game."This wasn't really as serious as last one," Staley said.Staley was examined by an independent neurologist on Monday. He must pass a battery of tests, as part of the NFL's protocol on concussions, before he'll be allowed to play in Thursday's game. "We're going through the process," Staley said. "We're going through a few different stages and I met with the neurologist yesterday. Everything went well there. And today, I have a workout, go on the field and see how everything goes with that."The short turnaround means it's more questionable that Staley will be available to play, but he said it is a good thing coming off the 26-3 loss to the Giants."For this team, it couldn't come soon enough," Staley said. "We got a bad taste in our mouth after last game on Sunday. So we're really excited to play, and we're not thinking about how quick of a turnaround it is. We just want to get on the field again."If Staley is unable to play, Alex Boone will move from right guard to left tackle. Veteran Leonard Davis would start at right guard. The 49ers are expected to list Staley as "questionable" on the injury report. A notification of his official status will not be announced until 90 minutes before game time.