GREEN BAY – As suddenly the Packers’ oldest veteran cornerback with a number of young prospects looking up to him, Sam Shields knows his every move is being watched.

It’s how he felt five years ago as an undrafted rookie, but for a completely different reason.

“When I came in, it was like that. I couldn’t make a mistake, or I was going home,” Shields said.

Shields isn’t going anywhere now except across from the opposing team’s top receiver. He embraces both the accountability and the leadership role that come with the duty, carrying on the mentoring he received from veterans such as Charles Woodson and Tramon Williams.

There are plenty of young guys looking to Shields, beginning with Green Bay’s first two draft picks, Damarious Randall and Quinten Rollins. After missing the first three practices due to a hamstring issue, Rollins took the field for the first time Monday, easing back into things.

Randall was the one making the big-splash play, intercepting a throw from Aaron Rodgers intended for Davante Adams in the back of the end zone, ending the No. 1 offense’s crack at the two-minute drill.

“That’s what the coaches are looking for, plays like that, so he can get the trust from the coaches, and from the older guys, too,” Shields said. “That was a good one.”

A handful of other first- and second-year corners are in the competitive mix as well, none more impressive so far than LaDarius Gunter. Undrafted from Miami, just like Shields, the quiet Gunter does far more listening than talking, the same approach Shields took back in 2010.

“Being an undrafted free agent, you have to do that, just bite a lot of bullets and keep working,” Shields said.

With Monday’s practice focused on red-zone work, Shields’ day mirrored the up-and-down play of the defense as a whole. The offense got the best of things early before the defense rose up later.

In one period, Shields was juked in the open field after a short catch by rookie receiver Ty Montgomery, and then Jeff Janis out-fought Shields for a jump ball in the end zone.

Later, though, Shields batted away a pass from Rodgers to Jordy Nelson, and he broke up a quick hitch to Janis.

“They caught balls, I made plays, but that’s how it goes,” he said. “You’re one-on-one out there. It’s me or him.”

 It’s the type of message he delivers to the young corners, never to get too hyped about a good play or too down about a bad one. Such is life at the position.

“I’m doing more talking, not out loud, but taking a guy one-on-one, helping him out, like ‘Wood’ did me,” Shields said.

Rollins didn’t take any team (11-on-11) snaps on his first day, but he hopes to do more on Tuesday.

Elsewhere on the injury front, linebacker Clay Matthews sat out practice with a sore knee while one of his replacements on the inside in the base defense, Nate Palmer, was practicing with his left hand clubbed up.

Palmer said he hurt the hand on Saturday, when he squared up to hit running back Rajion Neal in the hole. He made it through that workout but had the injury checked out later, and he says the club is a “day by day” deal for now.

Tight end Andrew Quarless practiced for the second time in camp after missing the first two workouts for personal reasons. He snagged a TD pass from scrambling rookie QB Brett Hundley during red-zone work.

Speaking to reporters for the first time, Quarless explained that his baby daughter passed away shortly after delivery last Wednesday.

“I’m so appreciative of this team,” Quarless said. “There’s just been so much support, more than I feel like sometimes I might deserve. It’s hard to explain it, how much that means to me. I’m just thankful and it really helps you put things in perspective. My mindset now is you really can’t take anything for granted.”