WASHINGTON — Exactly how high are the stakes for the Yankees in this regular season?

They’ll be able to file a first-person account by Thursday night.

The Mariners are coming to the Bronx for a three-game series, from Tuesday night through Thursday afternoon, and for a long time now, the only reason that news fired up anyone was to give ignorant Yankees fans an opportunity to boo the over-hated Robinson Cano.

This visit, however, will carry pennant-race consequences. The Yankees will get their initial look at the surprising (shocking?) crasher to this party of American League haves. In the process, they’ll formulate a better sense of just how crucial it is for them to capture the American League East.

“Obviously they’re a dangerous club, and they’re playing really well,” Aaron Boone said Monday of the Mariners, after the Yankees split a pair with the Nationals, losing 5-3 (the resumption of the May 15 suspended game) and winning 4-2 (a makeup contest). “They seem to have an offense that puts the ball in play. They’ve got some good players having good years. Their bullpen is deep with a really strong back end.

“It’s one of those teams that you feel like you’ve got to play really well if you want to have a chance to beat them.”

The Mariners, at 46-26, are on pace to finish 104-58. They reside in second place in the AL West, behind the Astros (49-25), who could finish 107-55 if they keep this up. The Yankees, 47-22 after Monday’s 1-1 effort, would finish 110-52 at this rate, whereas the 49-24 Red Sox would go 109-53.

Since only two teams out of that currently elite quartet can win division titles, that would leave the other two facing each other in the nerve-wracking, nail-biting, do-or-die wild-card game.

The Yankees received that tough draw last year, finishing behind the Sawx, yet it featured a soft landing in the form of the Twins, the Yankees’ perpetual punching bag, to whom they spotted a 3-0, first-inning edge before prevailing, 8-4.

How do you think the Yankees would feel about facing Seattle southpaw James Paxton without a safety net? Or, if the Astros hit a wall and finished behind the M’s, they could put the almighty Justin Verlander against Luis Severino.

Either scenario should motivate the Yankees to aggressively pursue any and all avenues that will land them the AL East title and the relative security that comes with a best-of-five series.

Of course, another clear path to safety exists, and the Yankees could chart the course this week: a market correction for the Mariners.

If you don’t think they’re playing over their heads, especially while Cano serves his 80-game suspension for illegal performance-enhancing drug usage, then you haven’t seen the Mariners’ modest 315-293 run differential, nor their amazing 23-10 record in one-run games. Maybe they can overperform their expectations all the way to October. Or perhaps reality will bite hard and open that hunt for the second AL wild card to lesser parties like the Twins or even the Tigers.

“It’s going to be fun,” Aaron Judge said of this series. “They’ve got a great ball club over there. Great pitching. Great offense. So, excited to see them.”

Judge contributed a pair of good defensive plays in Monday’s victory, including securing the last out — a Trea Turner bullet — on the right-field warning track with men on first and second. His fellow behemoth Giancarlo Stanton contributed a double and three singles after striking out twice in the first game, continuing his predictably roller-coaster first pinstriped campaign, and Aaron Hicks chipped in with a homer and a double.

The most exciting moment for the Yankees, though, occurred when young right-hander Jonathan Holder relieved Sonny Gray in the sixth inning with Nats on first and third and no outs and struck out Mark Reynolds and Daniel Murphy before retiring Pedro Severino on a pop to shortstop.

They can’t shrug off any win at the moment, not with the look of this AL landscape. It would greatly serve their interests to tweak that landscape this week by beating up on the Mariners.