Schwartz’s keys to the game:

YOUTH IS SERVED: First-round pick Ereck Flowers was supposed to get his NFL indoctrination at right tackle, but

Will Beatty’s torn pectoral forced a move into the lion’s den of pass protection. Flowers will be the first Giants rookie to open a season as the starting left tackle since William Roberts in 1984.

There’s a reason why coaches aren’t keen on a first-timer protecting the quarterback’s blind side. Flowers was very solid this summer, though he was far better as a run blocker than he was in pass protection — Pro Football Focus ranked him 31st out of 32 qualifying rookie tackles in pass blocking in the preseason. Up first for Flowers is Jeremy

Mincey, who led the Cowboys last season with six sacks.

“I like what I’ve always seen in him, OK?’’ Coughlin said. “He’s a rookie. He’s had good days, he’s had bad days. ... He’s a competitive kid who fights you. That’s not bad to start with.”

MONEY MANNING: Figure the four-year, $84 million contract extension is a relief to Eli Manning because it will end the questions he truly disliked addressing. Otherwise, Eli is Eli. He has a quarterback rating of 92.8 in 22 starts against the Cowboys and a rating of 86.1 in 10 season openers. He does have 46 career touchdown passes against the Cowboys (along with 23 interceptions) but a record of 11-11.

“He’s always the same,’’ Coughlin said. “That never changes. Totally involved, interested, always coaching somebody.’’

MEET YOUR NEW NEIGHBOR: It looks as if the Giants will have eight different starters on defense, with just Cullen Jenkins,

Johnathan Hankins and Dominique Rodgers-Cromartie returning from the unit that started last year’s season finale. The Giants were 29th in the league in defense in 2014, and that was with Jason Pierre-Paul.

The Cowboys have the NFL’s best offensive line, though they must show their running game can click without DeMarco Murray. Can this no-name defense — with rookie Uani’ Unga starting at middle linebacker for the injured Jon

Beason — hold the Cowboys under 30 points?

REAL STARS: The Cowboys head into this season as the top dog in the NFC East but also with a sour memory from the way last year’s brilliant season ended, blowing an 11-point lead in Green Bay in an NFC divisional playoff game — only after a Dez Bryant catch was overturned, in controversial fashion. It will be fascinating to see how the Cowboys respond to being the hunted. “I just figure if you haven’t won the Super Bowl, you didn’t win it the year before, then you probably didn’t finish the season the way you wanted to,’’ Tony Romo said. “For us, there’s a bitter taste, it doesn’t feel like, ‘Hey, that’s a happy go lucky’ kind of moment.