Throughout training camp and the preseason, two jobs in the Packers secondary were up for grabs: right cornerback and strong safety in the nickel defense.

After a season-opening loss to the 49ers, those positions are still unsettled.

“In the secondary, it’s a competitive situation,” coach Mike McCarthy said after Tuesday’s practice. He added that the Packers “don’t ever play with just 11 guys” and it didn’t inhibit anything by moving players in and out.

“The players’ performance dictates whether there is a lot of rotating,” McCarthy said.

On Sunday, physical veteran Jarrett Bush started over Sam Shields as the No. 2 cornerback and second-year S M.D. Jennings was back deep in the nickel. But Bush was tentative in coverage and beaten twice for big gains by San Francisco WR Randy Moss, once for a 20-yard reception and the other a 14-yard touchdown. Bush was also flagged for pass interference.

Jennings’ day was even worse. He was involved in a miscommunication on Moss’ score and he didn’t make a single play, except for the one that got him pulled from the game. On a third-quarter, first-down play, 49ers RB Frank Gore broke into the secondary for a 21-yard gain. Jennings had a point-blank opportunity to hit Gore but didn’t even touch him. He was immediately yanked in favor of rookie Jerron McMillian.

“I think I left a few plays on the field,” Jenning said. “It’s nothing I can’t learn from. I kind of gave [Gore] too much space. I just have to close the gap and do what I can to get him to the ground.”

The undrafted player out of Arkansas State said he wasn’t sure if the gaffe cost him the nickel safety job permanently. “We’ll have to wait and see how it plays itself out,” he said.

McMillian, a fourth round pick from Maine, is a physical defender who isn’t afraid to tackle. The Packers defensive backs have had issues bringing opponents down, so when McCarthy called McMillian’s effort on Sunday “solid,” it could only be interpreted as a good sign.

With so many young and unproven players in the secondary, McCarthy has called it a challenge to figure out the best group to put on the field.

“That’s where we are defensively as far as playing individuals based on personnel groupings," he said. "We do have a number of our guys that are, frankly, our role players. They need to focus on their role and perform at a higher level in that role.”

Charles Woodson, who certainly isn’t considered a role player, was actually encouraged by the defenses play against the 49ers.

“They put up 30 points, but I thought overall as a defense we made strides from where we were last year,” Woodson said. “We flew around. We got sacks. There were a couple plays here and there where we missed some assignments, but I come away from this game feeling really good about our team."

Follow Packers reporter James Carlton on Twitter: @CBSPackers and @jimmycarlton88.