The San Francisco 49ers will be facing a relatively unknown quarterback in Mason Rudolph on Sunday. That doesn't mean he isn't dangerous. Rudolph has appeared in one career NFL game — during Sunday's loss to the Seattle Seahawks in relief of injured Pittsburgh Steelers quarterback Ben Roethlisberger.

Roethlisberger is done for the year. Rudolph is the quarterback for the remainder of the season.

What does 49ers defensive coordinator Robert Saleh think of the Steelers' poised second-year quarterback?

"In my honest opinion, I do think Pittsburgh has got a really good quarterback sitting there with him," Saleh said. "You just watch his clips. He's got a good arm. He's accurate. He knows exactly where to go with the footballs, so you can tell that he's very well prepared.

"I'm just really impressed with his tape; much more so than I thought I'd be when I actually turned it on."

Saleh doesn't think the Steelers will have to change much with Rudolph leading the offense. Based on what he has seen so far, the defensive coordinator believes the young quarterback is capable of doing the same types of things Roethlisberger was able to do.

Saleh had to go back to the preseason film just to get a good look at Rudolph. One game, in particular, revealed a lot for Saleh. It was the matchup against the Carolina Panthers on August 29.

"People can disregard that (game because it is preseason) but I think he was in for 16 snaps, threw the ball 14 times, something like that," Saleh explained. "Just go through that tape if you guys are bored, and you guys want to watch it. He's at the line, he's very poised, [identifying] coverage, [identifying] his hot throws, taking his five-step drop. He's got great vision to the backfield to move people, throwing exactly where he needs to put the ball.

"He's quick with his reads, so the ball is getting out of his hands. If his first read is open, it is out. So he is very capable of playing quarterback, and it's our job to try to make it harder on him."

Cornerback Richard Sherman isn't discounting Rudolph either. He knows the Steelers are still going to try to do what they like to do and it doesn't matter if it is Roethlisberger or Rudolph behind center.

"He's still an NFL quarterback," Sherman said. "He's still going to be able to sling the ball around, so we've got to prepare for what the coordinator is always giving us, and he's been pretty consistent."

The veteran cornerback and the 49ers defense aren't taking any chances. They don't want to be the unit going against Rudolph when the quarterback proves himself.

"You've always got to prepare like you're playing their starter, and that's what we're doing," Sherman added.