Vikings safety Harrison Smith has been one of the best defensive backs in the league this season and he reminded everyone why early in the second quarter of Sunday's 30-14 victory at Oakland.

Smith delivered a punishing hit on Oakland's rookie wide receiver Amari Cooper in the middle of the field after a 15-yard gain. The aggressive play initially drew a flag, but was reviewed and determined to be legal.

The Vikings secondary limited the Raiders' big plays and gave up only two touchdown passes while intercepting two of Derek Carr's passes. Smith finished with six tackles in the game. Here's a look at his big hit:

Frame 1: The Raiders lined up with a single set back and wide receivers Cooper to the left and Michael Crabtree to the right. The Vikings are in a nickel defense with Captain Munnerlyn up in the box. Cornerbacks Xavier Rhodes and Terence Newman line up with Cooper and Crabree, while safeties Andrew Sendejo and Smith line up to the right and left, respectively.

"He's got what a lot of safeties, in my opinion, don't have," Vikings defensive tackle Sharrif Floyd said. "That nasty, that ability to throw your stuff in there and make great plays and sacrifice yourself for your defense. So that's what you should expect out of your safety and that's great on his end."

Frame 2: Cooper finds a hole in the middle of the field with five Vikings defenders surrounding him, but Smith adjusts quickly and isn't far behind Carr's completed pass. Smith steps up and delivers the hit moments after Cooper secures the ball.

"Well it doesn't hurt, unless it's the receiver," Zimmer said about the play. "We want our guys to be physical and give them a good shot but we're always trying to play fair and hitting them in the target zone. You know, Harrison's a big guy, and he's physical and tough, and he's going to get some of those shots. [Andrew] Sendejo does some of that as well. We have some big, physical, fast guys that we're always trying to hit them as hard as we can."

Frame 3: Smith is already locked in on Cooper and in motion when the pass is completed. By the time Cooper secures the ball, Smith is a few feet from him and already positioned to deliver the legal hit. The below frame shows Smith's steady progression and low point of impact leading with the shoulder and no contact to the neck or head.

"He did really good," Zimmer said about Smith's technique. "They throw a lot of those crossing routes on their boots, but the receiver caught the ball and kind of lowered like you do, so you have to adjust your angle on how you're going and he hit him with his shoulder and head was up, everything was good."