Aaron Boone watched more than four hours of horrific play from his team and there was no way the ultra-positive Yankees manager could sugarcoat an embarrassing performance in the biggest game of the season.

“We played poorly tonight, there’s no other way to explain it. And we need to flush this immediately because — we talked about it as a team, we need to get over this in a hurry and come put our best foot forward [Friday],’’ Boone said following a hard-to-look-at 8-3 loss to the Astros in Game 4 of the ALCS on Thursday night in front of 49,067 at a windy Yankee Stadium.

The victory gave the Astros a 3-1 advantage in the best-of-seven series that continues Friday, when the visitors can end the Yankees’ season in the Bronx. Cy Young candidate Justin Verlander starts for the Astros and the Yankees counter with James Paxton in a repeat of Game 2.

There was plenty of ugliness on display Thursday. DJ LeMahieu and Gleyber Torres each committed two fielding errors. The Yankees went 0-for-7 with runners in scoring position and stranded 10. They drew five walks in the first five innings and only scored a run in the opening frame. So good in Game 1 when he threw six scoreless innings, Masahiro Tanaka gave up four runs (three earned) and four hits in five-plus innings. Adam Ottavino’s miserable postseason continued by giving up a leadoff double to Alex Bregman in the eighth, when LeMahieu and Torres made fielding errors on back-to-back batters.

In addition to the sloppy play, the Yankees very likely watched CC Sabathia’s brilliant career end with a left shoulder injury. Sabathia exited the game in the eighth inning after throwing a 1-1 pitch to George Springer.

In order to get to the World Series for the first time since 2009, the Yankees need to win three straight with the last two in Houston and Verlander waiting for Friday night’s Game 5 and Gerrit Cole in a possible Game 7.

“Stranger things have certainly happened, a lot stranger,’’ Boone said of finding a way out of a very deep ditch. “And we need to play a cleaner game, obviously, if we’re going to beat a team like that. But we did not get it done tonight.’’

After taking a 1-0 lead against Zack Greinke, who walked Brett Gardner with the bases loaded in the first, the Yankees didn’t score until Gary Sanchez hit a two-run homer in the sixth that cut the Astros’ lead to 6-3. In the final three innings, the Yankees had two base runners and neither got on via a hit.

“You have to have a short memory, especially after a game like that,’’ said Aaron Judge, who went 0-for-4 with two strikeouts with runners in scoring position. “I had two to three chances to come through. I have to step up.’’

Tanaka breezed through the first two innings before walking Robinson Chirinos, the No. 8 batter, on four pitches to open the third. Josh Reddick followed with a single to right and Springer crushed a 1-0 pitch over the left-field wall.

“It starts with the walk first,’’ Tanaka said. “Nothing good happens when you walk the first batter.’’

And nothing good happened in a lot of areas for the Yankees, who are hitting a woeful .155 (16-for-103) in four games and an even worse 4-for-27 (.148) with runners in scoring position. In their last 14 at-bats in the clutch, the Yankees don’t have a hit.

“We didn’t play well tonight and it’s frustrating. But in the playoffs, you need to get past it,’’ Boone said. “You need to flush what’s already happened in a hurry because tomorrow’s too important.’’

There was a message on the clubhouse TVs in a very somber Yankees clubhouse. It read: “Friday Report 3:30 p.m. Travel Attire: Track Suits.”

Obviously the Yankees believe they can rebound. They won 103 regular-season games, dethroned the Red Sox as the AL East champs and swept the Twins in three ALDS games.

Yet there is a better-than-average chance those track suits won’t see the inside of an airplane headed to Houston.