What happens when the reinforcements’ reinforcements need reinforcements? The Yankees are about to find out. Again.

And this time, for the first time in recent history, they will be charged with finding the answer without having the safety net of potential August waiver trades at their disposal.

No Andrew McCutchen to provide help. No Jose Canseco to, er, uh, join the roster. What the Yankees have is what they will put on the field.

And they get this wonderful opportunity to test themselves now that Edwin Encarnacion has joined the burgeoning list of Men in Pinstripes on the IL after sustaining a fractured right wrist when hit by a Josh Smith 87.1 mph slider in the eighth inning of the Yankees’ 9-2 rout of the Red Sox in Game 1 of Saturday’s day-night doubleheader at the Stadium.

Not only that, they may have to go it without Aaron Hicks, forced out of the 6-4 second game victory with an elbow issue that developed on a sixth inning throw from center field for which he will undergo an MRI exam on Sunday.

At one time in The Bronx, it was about the straw who could stir the drink. Now, it is wondering about which straw finally will break the Yankees’ back. The question is not rhetorical as addressed by Aaron Boone.

“Any time your guys go down it’s frustrating and it’s tough. You feel for them,” the manager said. “But you know, we’ve dealt with this all season long and the next-man-up has served us really well.”

It has been a steady stream of next men up for this team that has had 24 different players account for 28 trips to the IL. Neither Luis Severino nor Dellin Betances have thrown a pitch this season, yet there were the Yanks a season-best 32 games over .500 after the sweep.

Giancarlo Stanton has missed all but nine games with a torn biceps, a shoulder problem and a right knee strain. Miguel Andujar, who finished second to Shohei Ohtani and ahead of Gleyber Torres in the 2018 rookie-of-the-year voting, is done for the year after having played a sum of 12 games.

Gary Sanchez is on the IL for the second time. Didi Gregorius missed the first 61 games. Aaron Judge was sidelined for 54 games. And yet here are the Yankees with an eight-game division lead.

“It’s kind of crazy,” said Hicks, who missed the season’s first 40 games with a back ailment. “Guys come back and somebody else goes down. It’s tough. We’ve been dealing with it the whole year but we’re still able to win.

“Next man up.”

Luke Voit and Greg Bird were the first-basemen fighting for the job during spring training. Then Bird went down before the middle of April with a left plantar fascia tear that has ruined yet another season. The Yankees picked up Kendrys Morales. He was bad, then injured and released. Then came Encarnacion from Seattle.

And now, with Voit on IL for the second time within five weeks with a core injury and Encarnacion now dealing with his plight, DJ LeMahieu is the everyday first baseman despite having started exactly one game at that position during his first seven seasons in the majors. He is at 12 this year.

You could, of course, do worse, considering LeMahieu leads the majors with a .336 average and has already set a personal best with 17 homers after smacking two in the opener. You could do much worse.

We have come to expect much from the Yankees, even if they have not been to the World Series since winning title No. 27 in 2009. We expect the laundry to fulfill outsized expectations that are commensurate with talent, heritage and, yes, payroll.

Three years ago, when the team fought its way into the playoff picture with a passel of kids following the deadline trades of Aroldis Chapman, Andrew Miller and Carlos Beltran, they were viewed as plucky overachievers. The same was true the following season with the unexpected dash to Game 7 of the ALCS. But after muscling up by adding Stanton during the 2017-18 winter, not so much.

Now, though, the laundry is being worn by Gio Urshela and Mike Tauchman and Breyvic Valera. Of course, it was Tauchman whose two-run single with the bases loaded and one out in the seventh broke the 4-4 tie in Game 2.

“I think the greatest strength of this team is being able to overcome adversity,” Tauchman said. “Next man up. Move the line.”

One man has gone down, another has stepped up. Time after time after time. At some point, though, the Yankees are going to run out of men. They trust the time is not now.