At least the Giants have the makings of a potent ground game. At this point, it may be all they have.

Another game, another sleepwalking performance by the Giants’ air attack. Thursday night’s preseason meeting with the Patriots at MetLife Stadium was Big Blue’s final dress rehearsal for the regular season, and it was supposed to be an easy tuneup against a bunch of New England backups.

Instead, Eli Manning was inefficient for a fifth straight August outing, and Victor Cruz went catchless for the fourth time in five preseason games. It was up to Rashad Jennings and the running game to rescue the Giants in the 16-13 win, and after the game, the Giants’ best receiver had to admit that the ground game could wind up carrying this offense next week, when the games start to count.

“The run game looks good,” Cruz said. “And it’s gonna be good for us to have that something that potentially we’re going to have to lean on as we’re working out the kinks.”

The eight snaps that the struggling first-team offense got were certainly filled with kinks. Manning completed just one of his four passes. His two drives were riddled with errors.

After Jennings opened the Giants’ first drive with two carries for 13 yards, Rueben Randle dropped Manning’s first pass. A play later, after a seven-yard Jennings run, Manning underthrew Randle, leading to a Steve Weatherford punt.

A possession later, after a short Andre Williams run, Manning overthrew Cruz, who had a step on his defender, then completed a pass for no gain to tight end Kellen Davis, a three-and-out against Patriot backups. The starters were done. “If they wanted to play more, they should’ve made some more first downs and stayed out there,” coach Tom Coughlin said.

But the rushing game was able to carry the Giants, just as it has for most of this preseason. Williams ended the first quarter by taking a handoff on fourth-and-1 from the Patriot 43, sliding right, waiting for a pair of blocks, breaking a Duron Harmon tackle and racking up 38 yards to the New England 5, setting up the game’s opening score, a 24-yard Josh Brown field goal.

After New England answered with a TD, a 33-yard strike from rookie QB Jimmy Garoppolo to Aaron Dobson, it was Peyton Hillis’ turn. Hillis, who missed most of the preseason with foot and ankle issues, carried 10 times for 37 yards on a 14-play, 80-yard drive. He capped the drive by diving across the goal line for a one-yard score, the Giants’ only TD of the game.

“I was dead dog tired, when I got down there,” he said. “Something overcame, and I wanted to get into the end zone.”

For the game, the Giants piled up 179 rushing yards, closing out a solid preseason, Jennings (six carries, 20 yards Thursday night) led the way, with 189 rushing yards on 29 August carries, and he may have to continue leading the way into the regular season if the passing game doesn’t come together.

But the Giants keep believing that their passing game will come together, even if it has shown very few signs in this preseason. Manning completed just 20-of-41 passes for 188 yards in the preseason, and he’s never seemed in sync.

But Coughlin has no choice but to believe that will all change.

“I think you have to have confidence,” he said. “We’ve had preseasons before where we haven’t had a lot of numbers, out of the offense particularly. Hopefully, that (doesn’t) carry over.”

Hopefully, said Cruz, the passing game will eventually be as productive as the running game. And then, the Giants will be dangerous.

“I think it’s good for us nevertheless,” he said of the Jennings-powered ground game. “And once the passing game kicks in, we’ll be a good, well-balanced team.”