Matt Kalil knows he didn't play up to his standards in the Vikings' season-opening loss to Detroit, but the Pro Bowl left tackle noted that he's not "freaking out" about it.

"It's not like, 'Ah, I got beat a couple of times, my season is over,' " Kalil said Wednesday.

His shaky start was an interesting development, however, because he performed at an elite level as a rookie but has looked sluggish since the preseason. Kalil said the increased tempo of a regular-season game contributed to his problems Sunday and that a flaw in his technique while using a silent count to combat crowd noise caused him to get "out of whack."

He described those issues as "little things" that are easily correctable.

"I know what I need to fix," he said. "I've got my mind straight this week. I'm ready to get after it. I'm not freaked out. I had a bad game. As bad as it was, I still didn't give up a sack … besides that guy that was offsides and crushed the quarterback. That really wasn't a confidence booster."

At least he hasn't lost his sense of humor. Kalil was referring to Lions rookie Ziggy Ansah, who jumped before the snap, zoomed past Kalil and drilled Christian Ponder in the back, causing a fumble. The offsides penalty negated the sack, but Kalil struggled with the speed and power of Ansah and backup Willie Young throughout the game.

His assignment doesn't get any easier this week against perennial Pro Bowl defensive end Julius Peppers, who Kalil admits was his toughest matchup of last season.

"As a left tackle, you've got to have a short-term memory," he said.

His problems Sunday were highlighted in back-to-back series in the second quarter. On first down, he sprinted to his left on a pitch to Adrian Peterson and missed his block on cornerback Chris Houston, who tackled Peterson for a 4-yard loss. On second down, Kalil missed his block on Ansah and stumbled. Ansah tackled Peterson for no gain.

On the ensuing series, Young beat Kalil around the edge and dragged Ponder to the ground. On the next play, Young got past Kalil again, forcing him to scramble to his left. Defensive tackle Ndamukong Suh applied pressure and hit Ponder's arm as he released the ball, causing an interception.

"I think sometimes I started overthinking things and started to get a little bit out of whack," he said.

Kalil had particular trouble containing the inside rush. He pinpointed the problem while studying film. On silent counts, he watched the ball and turned his head at the snap, causing him to drift and thus making him vulnerable to an inside move.

"It's things you don't notice in the games," he said. "I'm like, 'These guys are taking all these insides moves. I don't know why.' Then you look on film and I'm drifting out."

Kalil noted that he encountered a few rough stretches early in his rookie season, too. He became a rock at left tackle as the season progressed, solidifying the team's hope that he can occupy that position for the next decade.

Kalil realizes he "set a bar" as a rookie, which is why his struggles in the preseason and the opener have generated attention. His whiff on the first play of the Buffalo preseason game resulted in a sack. And he was called for two personal foul penalties in a span of six plays in the San Francisco preseason game.

"He's still a young guy, he's still learning," offensive line coach Jeff Davidson said. "Matt Kalil has to make sure that he has the mindset to go out and improve each game and not worry about what was, but what it's going to be."

To that end, Kalil is confident he'll return to form quickly.

"There are no excuses to it," he said. "I know how I have to play out there. I hold myself to a certain standard."