Four months might as well be four years, given how different are the New Orleans Saints (12-5) and Minnesota Vikings (13-3) from the teams that played each other in the regular-season opener Sept. 11.

The NFC Divisional Playoff game that will be played at U.S. Bank Stadium in Minneapolis on Sunday afternoon will be contested by teams that have morphed in ways that totally were unforeseen that Monday night, a 29-19 Minnesota victory that featured a 23-3 run by the Vikings.

The Vikings haven't been quarterbacked by Sam Bradford (346 yards and three touchdowns) since that night; Case Keenum took over and was the starter of record for the other 12 Minnesota victories. Likewise, rookie running back Dalvin Cook (22 carries, 127 yards) started three more games before tearing his ACL and being lost for the season.

Perhaps, the personnel changes have been even more drastic for the Saints. Eight players who started that game – left guard Andrus Peat, right tackle Zach Strief, running back Adrian Peterson, defensive end Alex Okafor, linebackers Alex Anzalone and A.J. Klein, safety Kenny Vaccaro and cornerback P.J. Williams – won't start on Sunday, with all but Peterson (traded to Arizona) and Williams (passed by Ken Crawley on the depth chart) out due to injuries.

Add in the scheme changes and philosophical nuances, and the result is past opponents who may find it almost useless to look at film of their prior matchup.

"I think both teams are different," Saints Coach Sean Payton said Monday in a teleconference with local media. "Now, there are some similarities in regard to scheme. But I think when you go through the course of an NFL season, you look at the attrition that takes place, there are eight or nine of our starters that were playing in that game that aren't playing in this game, and I'm sure the same exists for Minnesota. You begin to take shape as the season progresses as to who you become and I think both teams have done that."

The Saints, definitely, took on the dimensions of a more balanced offense, with the ground game taking center stage for a large chunk of the season and running backs Mark Ingram II (1,124 rushing yards and 12 touchdowns, 58 catches for 416 yards) and Alvin Kamara (728 rushing yards and eight touchdowns, 81 catches for 826 yards and five touchdowns) seizing the attention of the NFL during the regular season.

But, too, the Saints came on strong defensively. Bradford completed 27 of 32 passes in that season opener; after New England and quarterback Tom Brady completed 30 of 39 passes for 436 yards and three touchdowns the next week, the Saints went eight games before allowing another 300-yard passer, won the two remaining games in which they allowed three passing touchdowns and had 20 interceptions, 39 sacks and 16 touchdown passes allowed in the final 14 regular-season games.

"We're a lot more confident," linebacker Manti Te'o said. "We've been playing together for a while now, we kind of know the strengths and the weaknesses of the guys. We know how to play together, we know where people are going to be and so we're a lot more confident. We're a lot more confident in each other and we're a lot more confident and comfortable in the scheme.

"Definitely, to go from Week 1 to where we are now – Week 1, we were a relatively young team as far as experience goes and as far as time together. We've gone through a whole season now. We're definitely a lot more weathered, I would say.

"We've had our ups and downs throughout the season and whenever you go through that over the course of a 16-week season, that definitely helps you to identify who you guys are as a team and as a defense. I think we kind of know who we are and what we can do, and what our strengths are, and also the things we need to work on."

Ditto for the offense.

"We didn't know what we had in store when we first came out at the beginning of the year – we're messing around with a lot of options, a lot of different players, different things like that," receiver Ted Ginn Jr.  said. "But as the season went on we kind of found our mojo and who we are, and we've just been going on from there."

The Vikings managed to do the same thing. Particularly, Minnesota found – and kept – it's groove defensively.

"They're playing very well," Payton said. "They're tops in most categories defensively – I think total defense (275.9 yards per game), scoring defense (15.8 points), second in rush (83.6 yards), second in pass (192.4 yards). Offensively, they've found great balance. So it's a different type of team you're preparing for now and we're spending a lot of time, we will all week, on the more recent games and, quite honestly, the games throughout the season."