When the Vikings faced Green Bay Packers wide receiver Jordy Nelson at Lambeau Field on Christmas Eve 2016, their plan for dealing with top receivers was still in the process of being fully formed.

Xavier Rhodes had shadowed alpha receivers such as Calvin Johnson, Odell Beckham, Alshon Jeffery and DeAndre Hopkins, but he hadn't done it against Nelson. And even on the days when Rhodes would follow an elite wideout across the field, he'd stay at his normal spot when that receiver would line up in the slot.

With the metamorphosis of that plan not quite complete by last December, confusion reigned in the Vikings' secondary early in the loss to the Packers. Coach Mike Zimmer said after the game that Rhodes was supposed to shadow Nelson all day, only to see the Vikings' corners go against his plan and stay on their respective sides for the first series. And as startling as the development was, it didn't have much to do with the final result anyway: Nelson burned the Vikings for 81 of his 145 yards on three catches from the slot, when he was facing Captain Munnerlyn.

This time around, there might not be anywhere near the ambiguity about where Rhodes will be. After shadowing one receiver all game five times last year, he's already done it four times this season. And on several occasions, Rhodes has even started following his man into the slot.

He's been there for six snaps in five games this season, according to Pro Football Focus. But even if the Vikings have only used the approach sparingly, it can help them neutralize an opponent's one mechanism to get their top receiver away from Rhodes.

The latest wrinkle has meant an adjustment for the 6-foot-2 corner, who's spent most of his career lining up outside at right cornerback. He's had to learn some of the position's nuances, such as zone coverage rules and run fits, but in doing so, the 27-year-old is continuing his ascendance to the ranks of the NFL's best shutdown corners.

"Last year, he had a really good year, and now, it's like, 'OK, can we give him that next step? Can you go inside and shadow a guy without making a mistake?' " defensive backs coach Jerry Gray said. "He started doing a lot of that in training camp, and that was good for us to see. … When he's in there, it's not like he's totally playing nickel, but he's inside, as a nickel. If they run the ball your way, we expect you to make a tackle."

Said Rhodes: "They have a lot more room to work with. Playing outside, you can use the sideline to help. You have to be tighter [inside] and much closer in coverage."

The Vikings' first experiment with Rhodes shadowing a receiver, back in December 2014 against Johnson in Detroit, came in part because they didn't have another corner they trusted to handle the six-time Pro Bowler. He handled players such as Beckham and Hopkins last year, occasionally with the help of safety Harrison Smith in bracket coverage, and the Vikings have assigned Rhodes to Michael Thomas, Antonio Brown, Mike Evans and Marvin Jones this season.

Now, the Vikings are so used to Rhodes locking onto one receiver that they can structure their coverages to reap the benefits.

"When we have him shadowing, if we need to roll to a guy, take a guy away or double another guy, it gives you the ability to do that," Gray said. "You have to be really good to do that, knowing that I'm going to be the guy that's singled up."

However notable it is that Rhodes has added another wrinkle to his game, he only plays inside when his man lines up there, and Zimmer was in no mood to discuss it when asked about the change last week.

"Depends on the call. Really depends on the call," he said. "You're overthinking this. You're overthinking it. If you go back and whatever you're looking at to do it, I think if you go back and look at it, you'll find out that you're overthinking it. That is all I am saying."

Nelson will be far from the only receiver the Vikings have to worry about Sunday, when they face a Packers team with ascending wideouts Davante Adams and Geronimo Allison (not to mention veteran Randall Cobb and tight end Martellus Bennett). But if the Vikings decide to put Rhodes on Nelson this time, they can do so knowing there's nowhere he can go that the Vikings' top corner isn't equipped to follow.

"That comes with the business. It comes with the territory, the type of corner I am," Rhodes said. "I'm an aggressive-type guy. I like getting in receivers' faces. At the end of the day, whatever coaches tell me to do, I'll do it."

Ben Goessling covers the Vikings for the Star Tribune. Twitter: @GoesslingStrib. E-mail: ben.goessling@startribune.com