The giant fight to save their season and save their head coach at the same time is on.

It begins in earnest for Giants players Sunday against the Jets.

While The Post has learned from a well-placed source familiar with the club’s thinking that GM Jerry Reese is safe even if the Giants fail for a fourth straight season to reach the playoffs, there is uncertainty surrounding Coughlin’s future.

Tom Coughlin’s fate has not been decided, but if he wins the wretched NFC East, he shall return in 2016.

On the other hand, another late-season collapse would doom him.

Asked if there is any motivation to fight to keep Coughlin as head coach, Cullen Jenkins told The Post:

“It’s not just for him as a coach, but it’s for the whole organization. This is a team and organization that’s used to success, that’s got a history of success and reaching the playoffs, and … we have to fight for all of that. It’s been a long time since this team has made it to the playoffs, and it’s not acceptable around here, and it’s not the standard around here. And we’ve got a chance to still save this season, and still do some good things this year, possibly great things, but we got to do it one week at a time. We gave up an opportunity last week, so now we’ve got to buckle down even more, and take advantage of having one this week.”

There remains widespread respect for Coughlin, still hungry and driven at 69, in the Giants locker room.

“Everybody respects him,” Jenkins said. “You respect the heck out of him as a coach and as a person. He’s one of the most consistent people that I’ve ever met, where he comes in and he never complains, he’s in an upbeat mood, he’s ready to work every day, and he’s gonna try to motivate the team, he’s gonna try to get everybody going practicing good, paying attention in meetings, learning, getting better, and it’s every day.”

Is a head coach like that worth fighting for?

“Definitely,” Jenkins said.

“Love Coach Coughlin,” Prince Amukamara said. “I would fight for him regardless. We’ve bumped heads maybe three times out of the five years I’ve been here. I just have the utmost respect for him, and wish I could play for him all my years.”

Better beat the Jets first.