Early in the second quarter of the Vikings’ 25-16 victory over the Tennessee Titans on Sunday, Adrian Peterson powered into a pile to move the sticks on third-and-1.

The conversion gave the Vikings, trailing 3-0, a fresh set of downs in the red zone. They then got stuck in the mud after losing ground on back-to-back runs.

On the first, Peterson didn’t like what he saw as seven Titans defenders swarmed the offensive line. He danced in the backfield and was dropped for a 2-yard loss.

On the second, the Titans loaded eight defenders into the box. One was defensive end Jurrell Casey, who blew right by left guard Alex Boone, the Vikings’ prized free-agent addition, to wrangle Peterson down for another 2-yard loss.

“We’ve got [No.] 28, the best running back in the NFL. So we expect to see [crowded boxes] each week,” right guard Brandon Fusco said Monday. “We’ve just got to fix it and get after them. … If we keep working at this run game, we’ll get it going.”

In all, Peterson was tackled in the backfield on five of his 19 runs, including one that lost 5  yards. He had only three runs that gained more than 4 yards.

In was the third consecutive season opener in which Peterson, who has averaged 4.9 yards per carry in his career, mustered less than 4 per run. In 2014, he rushed for 75 yards on 21 carries in a win at St. Louis. Last season, it was 31 yards on 10 carries in a loss at San Francisco. Sunday, it was 31 on 19 at Tennessee.

From an efficiency standpoint, Peterson’s yards-per-carry average of 1.6 in the win was the fourth-lowest total of his career, which spans 121 games.

“Like always, it was a combination of things,” coach Mike Zimmer said. “There were a couple of times when we had it blocked really good on the front side, but the [defensive end] came all the way to the other side and made the tackle, which typically doesn’t happen. There was a couple of times where [the back] missed the hole. We got beat 1-on-1. [It was] different guys, not always one guy.”

Zimmer, however, didn’t believe a lack of chemistry with five linemen starting a game together for the first time was one of the contributing factors, nor did he think Peterson being held out of the preseason had anything to do with it.

He did, though, admit that all the Titans near the line complicated matters.

On 20 of the Vikings’ 28 running plays, there were at least eight Tennessee defenders in the box, according to Pro Football Focus. On 11, the Titans crammed nine defenders in there and dared Peterson to slalom through all of them or for quarterback Shaun Hill to check into a passing play and throw it over their heads.

Zimmer said “there was a couple” of plays when Hill aborted a running play that seemed likely to fail. But with Peterson, a first-team All-Pro last season, still in the backfield, the Vikings want to be persistent with the running game instead of letting opposing defenses dictate what they do by loading the box.

“There’s times where you have to run the football with extra guys in there. We understand that. It’s not going to go away. That’s how it was a year ago. When you’ve got Adrian in the backfield, you’re going to get those [looks],” Zimmer said. “If that’s the case, you’re going to throw it every down. There are some times where you get out of [run plays] and times where you have to man up.”

Last season, Peterson too often got stuffed at or behind the line. But the Vikings were able to take advantage of aggressive run defenses on several occasions by popping big runs.

They ranked second in the NFL with six runs gaining 40 or more yards, helping Peterson pace the league with 1,485 yards on the ground.

On Sunday, his longest run was 9 yards. But at least the big guys up front could feel good about how they fared in pass protection, a major issue in 2015.

Hill was pressured on 11 of his 34 dropbacks, according to Pro Football Focus, and hit four times. But the 36-year-old escaped the game without being sacked. Only three times last season did the offensive line pitch a shutout.

The improved pass protection helped Hill throw for 236 yards without coughing the ball up, which was critical in a game ultimately decided by turnovers.

“We did a pretty good job of keeping Shaun clean,” right tackle Andre Smith said.

Unfortunately for the Vikings, Peterson’s white pants were covered with grass stains after the season-opening victory. But the Vikings, who on Sunday night play host to the Green Bay Packers in their home opener at U.S. Bank Stadium, are confident they will get him going.

“It’s just some silly stuff that we need to clean up,” Fusco said. “We’ve always been a good running football team. So we’re not going to lose that.”