ST. LOUIS – As his Vikings lined up in the victory formation to tick down the final 91 seconds of Sunday's season opener, Mike Zimmer unsuspectingly stood on the sideline with his eyes focused on his starting quarterback.

Zimmer had been waiting a long, long time for this moment.

A respected NFL defensive coordinator for two decades, Zimmer several times was a runner-up for head-coaching positions. After he was passed over by yet another team this past winter, he briefly contemplated blowing off his interview with the Vikings, convinced that they wouldn't hire him either. But he went and they did.

Eight months later, he was watching Matt Cassel take a knee at the end of his team's dominant 34-6 victory — his first win as an NFL head coach — and never saw receiver Cordarrelle Patterson, whose 67-yard touchdown run was the highlight of the game, sneak up from behind and dump the orange Gatorade cooler over his head.

"I told them that I really don't want any more until I win the big one," Zimmer, still soaked, said after the game.

Zimmer was the first to admit that his new-look Vikings have a long, long way to go to get to a Super Bowl. But while Zimmer nitpicked the blowout win over the St. Louis Rams, he did feel a sense of satisfaction — and rightfully so.

His defense gave the Rams' quarterbacks fits and his offense stabilized after some early-game jitters in a wire-to-wire win over a physical Rams team that had legitimate playoff aspirations before losing starting quarterback Sam Bradford during the preseason.

Zimmer was hired in large part for his role in transforming the Cincinnati Bengals into a perennial top-10 defense, and while it remains to be seen just how high the Vikings defense might climb this season under Zimmer, the Vikings certainly didn't look like a team that would finish last in the league in scoring defense for a second straight season.

The Vikings recorded five sacks, picked off a pair of passes and allowed the Rams to convert just four of their 14 third-down opportunities. They knocked Rams starting quarterback Shaun Hill out of the game in the second quarter. And safety Harrison Smith officially made it a laugher late in the fourth quarter when he returned an Austin Davis interception 81 yards for a touchdown.

That aggressive, amped-up defense helped the Vikings earn their first traditional road win since the 2012 season.

The game was close, though, before a pair of fine individual efforts allowed the Vikings to pull away from the Rams.

In the final two minutes of the first half, cornerback Josh Robinson made a leaping interception, tapping two toes on the sideline to give the Vikings the ball inside Rams territory. Four plays later, Cassel found wide receiver Greg Jennings in the end zone to give the Vikings a 13-0 lead.

In the third quarter, Patterson put the game away with a highlight-reel touchdown run that brought back memories from late in his rookie season.

Patterson shifted from his wide-receiver spot into the backfield to take a pitch from Cassel. He rumbled toward the right sideline then cut back across the field, running through a tackle attempt from Rams All-Pro defensive end Robert Quinn and juking Rams cornerback Janoris Jenkins before being tackled into the end zone. The 67-yard run was the longest by a wide receiver in team history.

"As soon as he got that pitch, I saw a great block by [running back Matt] Asiata and I threw my hands up because I knew he had the ability to take it the distance," running back Adrian Peterson said.

The touchdown run silenced the crowd at the Edward Jones Dome, the same one that forced a few early false starts for the Vikings and led to one shotgun snap from center John Sullivan that Cassel didn't expect, though Cassel scrambled to pounce on the ball for a 19-yard loss instead of a turnover.

Zimmer surely shook his head at those miscues while watching tape of the game on the flight home. Ditto for the seven penalties and a handful of missed tackles.

He probably also looked to see which of his players gave him the celebratory Gatorade shower.

"I don't know [who did it]," he said. "I'll have to catch them, though. I'm sure it will be on tape somewhere."

While Zimmer, admittedly not the sentimental type, downplayed the significance of his first win as an NFL head coach while speaking with the media, his players made it clear how much winning this game for Zimmer meant to them.

"I'm sure it means something to him because I think every man in that room was excited for Coach Zimmer," said Cassel, who tossed touchdown passes to Jennings and tight end Kyle Rudolph. "This was his first win as a head coach. He's a guy that's been around this league for 20-some-odd years and he works hard. He's been a great coach and I think that to get his first win, we were all excited for him."

Matt Vensel • matt.vensel@startribune.com