San Francisco 49ers

49ers notes: Rookie CB Dontae Johnson could see more work vs. Bears

Vic Fangio made it clear Thursday: He expected big things out of rookie cornerback Dontae Johnson. But maybe not in the first quarter of the first game of the first season of his NFL career.

“I did think he was going to be capable,” Fangio said. “I didn’t know it was going to be that Sunday.”

Johnson, a fourth-round pick from North Carolina State, entered the game knowing he would see a lot of action on special teams. When both Tramaine Brock and Chris Culliver left with injuries, however, he wound up playing cornerback, too, and saw time against both of Dallas’ starting wide receivers, Dez Bryant and Terrance Williams.

Johnson knocked away two passes, including one on third down. Johnson also was covering Williams in the fourth quarter when he caught the Cowboys’ lone touchdown pass.

Culliver’s and Brock’s availability for Sunday night’s game against Chicago is unknown. Brock missed his second consecutive practice Thursday with a sprained toe. Culliver was in a blue, non-contact jersey during practice and is on track to be ready for Sunday. He still must pass the so-called “contact test” that’s part of the league’s post-concussion protocol in order to be cleared to play.

Perrish Cox almost certainly would start if one of the regulars can’t play. If both usual starters are out, Johnson and Chris Cook would be in the mix to start, Fangio said.

Johnson said that if he’s on the field, he expects to be targeted.

“Yeah, absolutely,” he said. “That’s just one of the things: ‘He’s a rookie. Let’s see if he can play this game.’ That’s one of the things that comes with being a rookie. You’ve got to be able to step up to the challenge, step up to the plate and make plays when (they’re) presented to you.”

Who the 49ers cornerbacks might cover also is fuzzy. The Bears have one of the top wide receiver tandems in the league in Brandon Marshall and Alshon Jeffery. Both, however, have missed practice this week with ankle and hamstring injuries, respectively. So has one-time 49er Josh Morgan, who is now the Bears’ No. 3 receiver. He’s missed practice with a groin injury.

If he sees time against Marshall (6-foot-4, 230 pounds) or Jeffery (6-3, 216), Johnson said his own size (6-2, 200) should be an asset.

“The trend that the NFL is leaning toward is taller corners to defend taller receivers,” he said. “But still, you have to be able to move and do everything a 5-10, 5-11 corner can do. So trying to do that, master my technique, master my footwork, I feel like it’s really helping me and (improving) my progress on the field.”

Secret weapons – Offensive coordinator Greg Roman said said receiver Bruce Ellington could help lighten Frank Gore’s and Carlos Hyde’s load at tailback this week. But he noted there were other options as well.

“(Fullback) Bruce Miller’s another guy that can tote the rock,” Roman said. “... We’ve been known to hand the ball to a lot of different people. So you never know. Be alert for (Joe) Staley on the reverse.”

Staley, the team’s 300-pound left tackle, is known for his light feet and he does have two career receptions for the 49ers. But he has yet to take a handoff.

Injuries – Anthony Davis (hamstring) still hasn’t practiced, making it more likely that Jonathan Martin will make his second consecutive start at right tackle.

• Justin Smith returned to practice after having Wednesday off.