The Lions — along with everyone else at MetLife Stadium on Monday night for the Giants home opener — will be looking for the look early in the game.

The look in Eli Manning’s eyes and in his body language will tell everyone — first and foremost the Detroit defense — a lot about how the game is going to go.

A week ago against the Cowboys at AT&T Stadium, it didn’t go so well, and the look in Manning’s eyes and in his body language told the story from the first offensive series on. The Cowboys defense saw the look, and their players relentlessly fed off it, never letting up.

They saw Manning frustrated. They saw Manning throw the ball into the turf to avoid getting hit. They saw Manning look like he was hesitant to throw the ball down the field. They saw Manning uncharacteristically inaccurate.

And it all played into the Cowboys’ hands until the distasteful 19-3 result was complete.

This is everything the Giants must avoid Monday night against the 1-0 Lions.

When Manning doesn’t trust his protection in the pocket, it shows up like one of those neon marquees in Times Square. That is when the aforementioned issues show up — all of which almost always lead to the Giants losing.

It is complicated criticizing Manning for being too cautious — which it appeared he was for a lot of the loss to the Cowboys, never trying to stretch their defense with a big play — because he has started 200 consecutive regular-season games for the Giants and another 12 in the postseason.

The Giants have no chance to succeed in the long term without Manning playing, so him being available every week is something that does not come with a price tag.

So Manning straddles a fine line between staying healthy and maintaining his impressive iron-man streak, which has him third all time among NFL quarterbacks behind just Brett Favre and his brother Peyton, and standing in a chaotic pocket a little longer trying to force a play when the team desperately needs one.

“Eli, like everyone else on the offensive side of the ball, had a bad night,’’ offensive coordinator Mike Sullivan said. “[He] had a night that is not up to our standard. [But] to rush to conclusions and where he’s at or where anybody is after one game, would be premature.’’

Blaming the Giants’ offensive line is warranted, because it struggled. But Manning sometimes needs to rise above that and find a way to make a play, and he knows it. He said as much in the aftermath of the Dallas loss.

The players on the Giants line, which has been enduring criticism as the weak link on the team since last season, also acknowledge they need to be better.

“We flushed it,’’ left guard Justin Pugh told The Post on Saturday of the Dallas loss. “We want to rewrite the story, the narrative that’s out there. We’re looking forward to doing that for sure.’’

Asked if he believes the firestorm of criticism of the Giants line is overblown a bit, Pugh said, “Yeah, people look at it as if we’re not running the ball well or the offense is struggling, it’s all the O-line’s fault.

“We’re like an easy target right now. People are just going to pile on right now. If they can’t make their own opinions, they’re going to go with whatever they hear, whatever they think is hot at the time.’’

Part of the sky-is-falling hysteria surrounding the Giants’ 0-1 start is the fact it was the season opener against their biggest division rival on national television, and it was so surprisingly one-sided.

Had the Giants beaten the Cowboys 30-10 or something like that, the same people who are now speculating about a potential 0-4 start would have the Giants already anointed as the NFC’s participant in the Super Bowl.

“That’s part of the business, we know that,’’ Pugh said. “Don’t get too high. Don’t get too low. That’s our motto.’’

Pugh called the mood in the offensive line meeting room this week as “upbeat and positive.’’

“We’re ready to go,’’ Pugh said. “No one wants to get better more than we do. No one wants to right these wrongs more than we do. We want to go out there and play well. That’s our goal, that’s our plan. If not, we’re not going to have jobs.’’