Underwood took the plunge prematurely in the end zone after scoring on a 30-yard interception return.
Shields correctly waited until getting beyond the end zone after his pick and 99-yard runback but made an awkward jump into the front row of seats.
"It was exciting," Shields said. "It gives you the chills with all the fans patting you on the back, congratulating you."
While their celebratory form needs some work, the big plays by the two young cornerbacks were an uplifting revelation.
"That's what you want because when the ball is in the air, as we have demonstrated in the past, we have playmakers on defense that when they get their hands on the football they are able to do something with it," coach Mike McCarthy said.
The Packers were ballhawk masters in 2009, leading the league in interceptions (30) for the first time since 1965.
While Woodson was one of a few veterans excused from participating, Harris still is on the mend from reconstructive surgery on his left knee late last year.
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Woodson, who will be 34 in October, also is no spring chicken, even after being the league's top defensive player last season.
"Just for the vets, they've got to be able to feel comfortable with everybody's that out on the field," Underwood said. "They've got to be able to know that whoever's number gets called ... they're going to be ready to perform on Sundays."
Williams, originally signed by the Houston Texans as an undrafted player, has made strides the last three seasons with the Packers. He's been primarily their nickel back but has 20 starts under his belt and is the starting fill-in for Harris this preseason.
The domino effect of Harris' injury rehab has Underwood and Lee battling for playing time in the nickel role.
Lee, a third-year player, is healthy after missing last season because of a knee injury.
Underwood, who played sparingly as a rookie last year, has managed to put aside the distraction of being accused of sexual assault by two women at a Wisconsin vacation resort in June. The case remains under investigation.
"He's done a nice job for us this camp and a guy who, I think, has grown up definitely in the last couple of months," quarterback Aaron Rodgers said.
Rodgers was most impressed after a week of training camp with Shields, an undrafted rookie who converted from wide receiver at Miami (Fla.).
"Obviously, he has ability," Williams said. "You see the speed. He's got a lot of ability. I think he's going to be here."
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Bill Huber is publisher of Packer Report magazine and PackerReport.com and has written for Packer Report since 1997. E-mail him at firstname.lastname@example.org, or leave him a question in Packer Report's subscribers-only Packers Pro Club forum. Find Bill on Twitter at twitter.com/packerreport and Facebook under Bill Huber.