NEWS UPDATE: Rookie WR Dominique Johnson, who was having a poor camp, was released. Rookie LB Kyle O'Donnell takes his spot on the roster.

It's never good news when a 31-year-old, 300-pound, five-time All-Pro defensive tackle has plantar fasciitis and has to rest for at least the next two weeks. But the Vikings do have a good eye for young defensive linemen, so there is some promising depth behind Kevin Williams, the aforementioned All-Pro with the bum wheel.

In fact, the depth all along the defensive line is one area that's jumped out during the preseason and training camp. Here's one person's opinion on the top three potential sleeper breakout candidates for this season. And all three are on the defensive line:

1, Letroy Guion, tackle.

Letroy came into the NFL as a fifth-round draft pick in 2008. He was a tall inside player with good pass-rushing skills. He's become a more well-rounded player, stopping the run while keeping that quick step across the line. Guion has been part of the team's D-line rotation for awhile, but this could be a big year for him as Williams' primary backup. Williams won't be in top condition when he returns from the foot issue. There's also the possibility the issue will linger. And there's also the looming possibility of Williams having to serve his four-game suspension for testing positive for a banned diuretic in 2008.

2, Everson Griffen.

Griffen was a first-round candidate who fell to the Vikings in the fourth round last year. Off-the-field behavior played a role in his tumble. If he can stay out of trouble, Griffen can make teams regret passing on him for three rounds. On the field, Griffen has shown improvement this year. He's shown a speed rush, some power and a mean streak that makes one think Griffen's starting to take this thing seriously. He's Jared Allen's primary backup, but can play either end position. He'll be the first end off the bench.

3, Christian Ballard.

Could be a real bargain as a fourth-rounder. He looks like a defensive end and has some pass rush skills like an end, but the Vikings have kept him inside at the same three-technique position that Williams plays. That means Ballard becomes a big part of the rotation if Williams misses time during the season. There's weight-room strong and big-old-country strong. Like Williams, Ballard appears to be big-old-country strong. Not that they don't work hard in the weight room. They just have that big-boned power. And when you mix it with some quickness inside, like they have, it's tough to block.

Other candidates: Left defensive end Adrian Awasom. He's the No. 2 left end and looks like he can become a legit NFL pass rusher; Tight end Allen Reisner. No undrafted rookie has turned more heads than the big kid from Iowa. He's got the size, the hands and enough speed to make it somewhere. The only question is why he chose to come to a team that's loaded at tight end. He'd make a nice practice squad player if he doesn't end up being taken by another team; Linebacker Larry Dean. He's small at 6-foot, 226 pounds. But last year's D-II Defensive Player of the Year is instinctive, fast and just puts himself around the ball. He could surprise people if he can latch on as a special teamer.