The only way the Giants will consider Jason Garrett for their head coaching job is if Matt Rhule fumbles his interview with the team on Tuesday.

That’s according to The Post’s Paul Schwartz, who reported Monday that the recently whacked Cowboys head coach “is a fallback option” the Giants will consider — but only “if things go sour with Rhule.”

Rhule, the highly touted Baylor head coach and the favorite to land the Giants job, will meet with the franchise’s brass in New Jersey, where co-owner Steve Tisch will be in attendance.

That is noteworthy because Schwartz reported, “Tisch has not been present for every interview; if he wasn’t there in person, he phoned the candidate after the formal interview.”

Rhule on Monday met with the Panthers at his Texas home, but the Giants head coaching job seems to be his to lose, with the Cowboys hiring former Super Bowl winner Mike McCarthy a day after parting ways with Garrett.

Garrett was linked to the Giants during his final season with the Cowboys, but the Giants seem to have their eyes set on Rhule, the 44-year-old New York native who resurrected Temple and Baylor and served as an assistant offensive line coach for the Giants in 2012.

The Giants have already interviewed five other coaching candidates, including McCarthy, and were waiting for Rhule to return from vacation following the end of his college football season.

For more on the Giants, listen to the latest episode of the “Blue Rush” podcast: