EDEN PRAIRIE, Minn. -- After nearly four months of evaluation, a handful of injuries and the release of two veterans over the weekend, the Minnesota Vikings still apparently haven't settled on a starting safety opposite Harrison Smith -- at least not one coach Mike Zimmer was comfortable sharing on Monday.

"I don't know yet," Zimmer said when asked who will start next to Smith in the Vikings' regular-season opener against St. Louis on Sunday. "We'll see."

Robert Blanton has been atop the depth chart since the Vikings released their first one during training camp, and seems like the logical pick to start next to his former Notre Dame teammate. Blanton missed part of training camp with a hamstring injury, but came back before the Vikings' third preseason game against Kansas City and seems healthy now.

"He's a smart guy," Zimmer said. "Sometimes when you make the transition from corner to safety (as Blanton did), it takes those guys a while, but he's a smart guy. You have a little bit more athletic ability, usually."

Smith said he won't be affected in any major way by who starts next to him on Sunday, and was coy when asked if he knew who the starter would be. It seemed like Smith's partner might be 34-year-old Chris Crocker, who came out of retirement for a third consecutive year to play for Zimmer and started a pair of games next to Smith in training camp.

The Vikings, however, released Crocker on Saturday, along with Kurt Coleman, when they concluded they "had a lot of the same guys," as Zimmer put it.

However short his time was with the Vikings, though, Crocker helped Smith's development in the team's defense.

"He was like having a coach in the locker room, in the meeting room, on the field," Smith said. "In between plays, he'd say, 'Hey, Harry, watch out for this coming up here,' and he was right most of the time. Even though he was only here for a little bit, I learned a ton from that guy.

"Just having that time with Crocker was good. I kind of had Antoine (Winfield) to look to when I was a rookie, just to see how a pro prepares. I never really had a safety to look at who was an old, old guy -- I called him the 'old man' every day. He kind of showed me again what it was like to be a professional and to really understand the game."

Should the Vikings start Blanton on Sunday, his experience in coverage will likely be a big part of the reason he's got the job. The Vikings will put their safeties in man coverage much more often than they did in their old regime, and Blanton seemed to separate himself from competition during the team's OTAs and minicamp because of his coverage skills.

"It's going to be fun for us (safeties)," Smith said. "We get to do pretty much everything, all levels of the defense: down near the line, dropping down like linebackers, playing deep, covering man-to-man. We get to do pretty much everything."