Josh Robinson had a momentary brain cramp, which was perfectly understandable, given the amount of energy he had expended defending a pair of jumbo-sized receivers on Sunday.

Assessing his performance in the Vikings' 21-14 victory against the Chicago Bears, Robinson referred to himself as a "freshman."

Um, freshman?

"I mean rookie," he said, laughing. "Good call."

A fellow freshman, er, rookie stood 2 feet away inside the Vikings locker room.

"He might say [he's a freshman]," safety Harrison Smith said, "but that's not how he plays."

Rookie, freshman, whatever you call them. The two youngsters made a pair of game-changing plays that allowed the Vikings to keep their season afloat on a day when the offense once again revolved almost exclusively around Adrian Peterson's brilliance.

Robinson's first-quarter interception and return left the Vikings in the shadow of their goal line, setting up a point-blank Adrian Peterson touchdown run for a 14-0 lead.

Smith's pick-six in the third quarter proved to be the deciding score and gave him three interceptions on the season, the most by a Vikings rookie since Orlando Thomas grabbed nine in 1995.

The two rookie defensive backs also gave up some big plays to Jay Cutler and his two towering receivers, Brandon Marshall and Alshon Jeffery. But their interceptions directly led to 14 points, and they actually combined for more return yards (100) than the Vikings generated in receiving (91), the latest indictment on the team's feeble passing game.

"I know those guys are excited," veteran cornerback Antoine Winfield said. "I'm sure we'll be out having some fun [Sunday night]."

Presumably, Winfield didn't make the rookies pick up the tab this time, if for no other reason than he doesn't consider them rookies anymore. "Oh, no, no," Winfield said. "We're 13 games in. No, you're not a rookie. I think after five games, you have to drop that title."

Smith and Robinson officially lose that label at season's end, but their on-the-job training can't be overstated in its importance in regards to their future. The Vikings appear to have found a bona-fide playmaker at safety in Smith, who is tied with Winfield for the team lead in interceptions and ranks fourth in tackles. Robinson plays extensively in the nickel back role and is being groomed as Winfield's replacement.

The pair had no choice but to grow up fast after being drafted in a division with superstar receivers (Marshall, Calvin Johnson) and elite quarterbacks (Cutler, Aaron Rodgers, Matthew Stafford).

"The thing that stands out to me is that everybody is good," Smith said. "There's no slouches out here. Everybody can make plays. Every week is a big challenge."

Sunday was no different, but the rookies showed they're also capable of making timely plays. On the Bears' second possession, Jeffery stumbled as he ran his route, leaving Robinson with a clean interception near midfield. Robinson returned it for a touchdown, but the Bears challenged and replays confirmed that he stepped out of bounds at the 5-yard line after hurdling a defender.

"We were still able to put the offense in good position," Robinson said.

Smith took things a step further after Cutler overthrew Marshall in the third quarter. Positioned perfectly in the middle of the field, Smith weaved through traffic and then raced to the end zone for a 56-yard touchdown. "I guess it's good that I got to play some running back in high school," he said.

The rookies took some lumps Sunday, too. Jeffery beat Robinson off the line, and Smith's help over the top was slow, resulting in a 23-yard touchdown pass. Both took responsibility.

"That one's on me," Robinson said.

Said Smith: "I would have liked to get a better break on that one."

They also had their hands full with Marshall, who was targeted 19 times and finished with 10 catches for 160 yards and one late touchdown with Robinson hanging on his back. Smith described Marshall as a "freak," and Vikings defenders marveled at the receiver's combination of size and skill and Cutler's willingness to throw him the ball in any situation.

"A guy that's 6-5, great hands and long reach," Winfield said. "I'd take my chances, too."

The Bears took advantage of that mismatch, but the Vikings made a few pivotal plays to offset that. And their rookies grew up a little bit more. They shouldn't feel like freshmen anymore.