"He did a heck of a job this week. He looks good. I would anticipate that he'll play quite a bit - possibly start. You might even say probably start at this point - that would be my anticipation right now," Harbaugh told reporters. "Unless something changes between now and then, he'll be the starter at left tackle, and we anticipate all those guys playing and being a part of the game plan."
That means Harbaugh still anticipates a role for Bryant McKinnie, who is being unseated on quarterback Joe Flacco's blind side.
Ngata will play Sunday, the coach said, even though he didn't practice Wednesday and Thursday.
"We gave Haloti a few days. He had little tweaks and strains and things like that, so we gave him a couple days," Harbaugh told reporters. "But he looked good today, so he's going to play. He should be fine."
As for McClain, reports surfaced Wednesday that he was cleared to return to action after a spinal cord contusion forced him to miss the team's last eight regular season games dating back to December.
Harbaugh addressed that for the first time Friday.
"I think it was reported that he was cleared, and there is some truth to that," Harbaugh told reporters. "The back specialists have looked at his most recent MRIs, and it's very favorable. I'm not in position to sit here and say completely 100 percent - I don't know that. There is a process still involved, but it's encouraging to say the least. It's all positive that way."
McClain is on the physically unable to perform list and is eligible to practice next week.
"Well, he could. That's something that we'll have to decide," Harbaugh said. "There will be a couple factors that go into that - timing-wise, his shape, our situation. That's just something we'll have to see. He hasn't played for a long time. What do the doctors tell us about his readiness that way? So, we'll just have to see. But I know that he can by rule."