BEREA, Ohio (AP) -- Josh McCown slid a little closer to starting the Browns' home opener.

Still making progress after sustaining a concussion while trying to dive into the end zone for a touchdown against the Jets last week, McCown is expected to be cleared to practice Friday. As long as he gets medical clearance and gets on the field, coach Mike Pettine indicated he will play his starting quarterback over Johnny Manziel on Sunday against Tennessee.

"We've discussed it, and I think it still will be our decision based on how practice goes," Pettine said Thursday. "But I don't see an issue if he's cleared and practices fully tomorrow, barring anything unforeseen, a reason why we wouldn't play him."

McCown has been restricted by the NFL's protocol on concussions from practicing over the past two days. He has attended meetings and been on the field watching as the Browns install their game plan for the Titans.

On Thursday, the 12-year veteran was in the locker room but the team kept him off limits from any interviews.

Offensive coordinator John DeFilippo said McCown has been as involved as usual this week.

"I don't notice any change in Josh," he said. "He's been in the meetings. He's been attentive. He's been himself."

The Browns would prefer to play a seasoned McCown ahead of Manziel, who came in during the first quarter last week in New York. Manziel looked better than he did during either of his starts as a rookie, but the former Heisman Trophy winner offset his first career touchdown pass with two fumbles and an interception.

It's possible the Browns don't want to subject him to Hall of Fame defensive coach Dick LeBeau, now with Tennessee. LeBeau built his reputation on how his defenses in Pittsburgh used to take apart young quarterbacks.

Manziel has taken the majority of snaps with Cleveland's starting offense this week, but he could wind up returning to his backup role if McCown makes it through Friday's workout.

"That's part of it," Manziel said, resigned to his possible fate.

Browns Pro Bowl tackle Joe Thomas said Friday's practices are the most important of the week because that's when the team fine tunes its game plan, throwing out plays that didn't work and tinkering with others. If McCown is on the field, Thomas expects him to start.

"I don't think he would have any problem stepping in without missing a beat," Thomas said.

Pettine said McCown's absence from the past two practices and the initial installation of the game plan is not a major issue because Tennessee's defense is similar to New York's.

"When we game plan for the first quarter of the season and started to works some of that stuff late in training camp, it carries over," he said. "If this was a completely different plan and it wasn't this close to coming out of training camp, I think the situation would be different, but he's gotten quality reps on a lot of the elements of the plan that we have up."

McCown will be examined by an independent neurologist to determine whether he can practice, and Pettine said there is no need for a follow-up exam once a player is cleared.

Pettine said it's impossible to know whether McCown will receive permission to participate in the week's final practice.

"There's no Ph.D. after my name," Pettine said. "So that I do not know. We're hopeful, optimistic. To me, these situations you learn over time, they're just impossible to predict."