LOS ANGELES – Thursday night was no time for Xavier Rhodes to lose his cool and be forced to the sideline for even one play to compose himself.

Not in a game like Rams 38, Vikings 31. Not when quarterbacks Jared Goff and Kirk Cousins completed 62 passes for 887 yards and eight touchdowns. Not when Goff posted a perfect passer rating of 158.3.

With 1 minute, 41 seconds left in the second quarter, Rhodes was flagged for his second holding penalty of the game. The first one turned a third-down stop into a Rams touchdown drive and a 7-7 tie in the first quarter.

The second one should have been harmless. It came on first-and-10 at the Los Angeles 27-yard line. The Rams completed an 11-yard pass on the play, so they declined the penalty.

It should have ended there. But it didn't.

A frustrated Rhodes kicked the penalty flag. Officials frown upon such actions, so the guy who threw the flag for holding then threw his hat, signifying another penalty on Rhodes.

This one was 15 yards for unsportsmanlike conduct. The Rams marched to the Vikings 47-yard line.

Rhodes, meanwhile, went to the bench to serve a one-play timeout in coach Mike Zimmer's penalty box.

"Yeah, well, he kicked the flag," Zimmer said of his reasoning. "That's the kind of things we've been doing. Having penalties on defense and giving up big plays. It reared its ugly head again tonight."

Until Rhodes went to the bench, he had shadowed Rams receiver Brandin Cooks, a prized offseason acquisition from the Patriots. At that point, Cooks had been targeted twice, catching one ball for 12 yards.

Goff certainly noticed the defensive personnel change. With Trae Waynes on Cooks, Goff launched a well-placed deep ball past Waynes for a 47-yard touchdown and a 28-17 lead. And, to make matters even worse, Waynes suffered a concussion on the play.

Rhodes returned for the next series and held Cooks to 57 more yards on five more catches. But the damage had been done, thanks to Rhodes' tantrum.

Goff threw the ball 33 times, completing 26 for 465 yards, five touchdowns and that perfect passer rating.

The Rams had seven plays of 20 yards or more. They had a 70-yard touchdown pass to Cooper Kupp. They had a 56-yard pass to running back Todd Gurley. They had a 36-yard pass to Robert Woods. They had three guys top 100 yards receiving.

"Any place I've ever been, we've never been this poor in pass coverage," Zimmer said. "We have to look at what we're doing and get back to doing things right quickly."

Zimmer has a point. Especially with the Vikings sitting at 1-2-1 and heading to Philadelphia to face Carson Wentz in the stadium where the Vikings lost 38-7 in last year's NFC Championship Game.

"[Zimmer] is spot on," safety Harrison Smith said when asked about Zimmer's assessment of the defense. "You can't play like that and expect to win in the NFL."

So, Harrison, what's the difference between this year's defense and the one that led the league in fewest points and yards allowed just a year ago?

"I can't point to it as a player," Smith said. "We got to bring more fight. We have to take care of our jobs.

"There's no Superman. There's none of that. Everybody's got to handle their job and get back to running around out there and having fun. Knowing we're going to make plays."

And more composure is needed. Especially from a first-team All-Pro cornerback now in his sixth NFL season.

Rhodes' temper cost him one play on the bench. Goff turned that one play into a 47-yard touchdown and a two-score game.

"We have to be better than that," linebacker Anthony Barr said. "Every week, you play a good team in the NFL."

And a struggling defense can't afford having one of their best players benched to compose himself.

Mark Craig is an NFL and Vikings Insider. Twitter: @markcraigNFL. E-mail: mcraig@startribune.com