QB Thaddeus Lewis played in the preseason but hasn't in the regular season. That could change Sunday. (US Presswire)
Browns quarterback Thaddeus Lewis isn't accustomed to the spotlight. In fact, he has never played in an NFL game.

That could change on Sunday in Pittsburgh. Starter Brandon Weeden and backup Colt McCoy both missed practice on Wednesday with right shoulder injuries. The Browns have signed veteran Josh Johnson, but Lewis is taking the first-team reps.When Lewis faced the cameras in the first extensive interview with the media of his professional career, he felt a bit overwhelmed.

"I wouldn't say I was a celebrity," he said with a smile. "The lights are bright, though."

They will also be bright in Pittsburgh, where the Browns will try to avoid a three-game losing streak to end the season and Lewis could be "living out a childhood dream" if neither Weeden nor McCoy is available. "If my number is called, it's going to be amazing," he said.

Lewis was an undrafted rookie free agent out of Duke before latching on in 2010 with St. Louis, where then-offensive coordinator Pat Shurmur became impressed with him. The Browns signed him just before the regular season in 2011, Shurmur's first as head coach in Cleveland. Lewis' last start was with the Blue Devils in a loss to Wake Forest. In three years at Duke, he threw for 10,065 yards and 56 touchdowns and was intercepted 24 times.

"I've had experience with Thad in the past," Shurmur said. "He hasn't had a lot of opportunity in regular season games to go in there and play, but if he's in there playing, we definitely trust that he'll do a good job."

What does that mean to Lewis?

"It means making plays, making the right reads, being a leader and putting guys in position to make plays," Lewis said.

That's no small task against a Steelers defense that remains one of the best in the NFL.

"I wouldn't say I'm intimidated," he said. "I just love to play out there, no matter where it is."

Injury report: The Browns were healthy two weeks ago, but not anymore. Their quarterback situation is not all that has worsened since they traveled to Denver.

The secondary is a particular mess. Free safety Usama Young has been placed on injured reserve with a thumb injury that will likely require surgery. Cornerback Sheldon Brown (concussion) did not practice on Wednesday. The return of Tashaun Gipson (foot) to practice should result in him playing safety alongside Eric Hagg, though it remains unknown who will start at the free safety position and who will start at strong safety.

Featured back Trent Richardson (ankle) was also sidelined on Wednesday. If he remains out, he will conclude the season 50 yards short of 1,000. The rookie appeared a few weeks ago to be a shoo-in for that milestone.

Richardson would be replaced as the starter by Montario Hardesty, whose 4.6 yards per carry this season is a full yard better than that of Richardson. Hardesty sees possibly starting on Sunday as an opportunity to prove himself.

"When I get my chance, I have to make sure I maximize my opportunity," he said. "That's what I've been trying to do. It's exciting to get the opportunity to play ball and if I get more carries, I'll welcome that with open arms."

Bringing down Big Ben: DE Juqua Parker, who leads the Browns with six sacks, understands that adding more against Steelers quarterback Ben Roethlisberger on Sunday will take a concerted effort.

"Ben is a big guy," he said. "He's hard to bring down. We can bring him down, but you have to make sure that when you hit him, you hit him. If not, he's not going to fall."

Roethlisberger has struggled mightily in recent weeks with injuries to his shoulder and his ribs, the second of which doctors warned was a threat to his aorta. He has been cleared to play, but has not performed anywhere near his standards. He completed just 14 of 28 passes and was intercepted twice in the loss last week to Cincinnati that knocked the Steelers out of the playoff race.

Shurmur, however, is not about to take comfort in such numbers.

"I wouldn't say [Roethlisberger] is not on top of his game," he said. "I've still seen the same plays that you see him make where it looks like the play is dead, he extends it and finds a receiver."

Stay dialed in on the Cleveland Browns on Twitter at @CBSBrowns throughout the season with on-site updates from CBSSports.com RapidReports correspondent Marty Gitlin.