The Giants are about to find out.

If their offense is as good as they think. If their defense is better than others think. If they can snap out of the doldrums of three straight playoff-less seasons and two straight years with a losing record.

"Fellas," Tom Coughlin said he told the players about the start of the season, "buckle your seat belts."

And if he is basing that sentiment on the preseason, he might as well add that they should put their tray tables up in a locked position and prepare for some bumpy air.

In their four summertime frolics, the Giants showed very little to inspire much confidence, managing only one touchdown drive with their starters. But the objective in those games was far different from what it will be in Sunday night's season opener against the Cowboys.

"It's like all a learning process," Odell Beckham Jr. said of the preseason. "You want to get all your flaws out, seeing what works and what doesn't work. We were able to get a good look at that."

They sure were.

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And now it becomes real. Some Giants already have termed this a "must-win" game. Others might not go that far but recognize the significance.

After four straight Week 1 losses, the Giants would like to start a season with a win. In the previous two seasons, they spent only one week with a record over .500 -- they were 3-2 last year -- and a win in Dallas instantly would give them another.

"They have to be ratcheted up, so I'm ratcheting them," Coughlin said. "We talk about game-day culture around here. Well, that's what has to happen in practices. Somebody has to show me that they do get it, because you are playing in a whole different kind of context. It's not preseason. People aren't counting snaps. I start the week off with that one. 'Guess what? You were tired last week with 30 [snaps]? Guess what, you've got 70. Be ready.' "

Quietly, the Giants believe they are. Especially on offense, where vanilla play-calling is about to become a more extravagant flavor. They just hope it's not rocky road.

"It wasn't as crisp as we wanted it to be in the preseason," offensive coordinator Ben McAdoo said. "We didn't get a ton of reps with the first group. That's usually the way it goes. We looked a lot better in practice, but most teams do. We feel that with the last few days of work that we have that we can go out and look crisp on Sunday night and put a good product on the field."

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Beckham agreed.

"Being able to put in stuff that we're going to use and game plan for another team, now you know what your scheme is and what your goals are and where you're trying to attack, it makes it all the more better," he said. "It's game time now."

McAdoo was asked if he is concerned about the tepid offense of the preseason carrying over into the regular season.

"No," he said. "Not one bit."

We'll find out soon enough.

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"Whether you're ready or whether you're not ready, it's starting Sunday night," Coughlin told his team, but he quickly pointed out that it wasn't really a choice.

"And you'd better be ready."