Anybody who seriously believes having home-field advantage in a best-of-seven October series isn’t a big deal probably still thinks the world is flat.

When it comes to the Yankees’ final 27 games, securing that advantage is the only remaining goal as they hold a whopping 11-game lead over the second-place Rays in the AL East. The Yankees’ magic number to clinch their first AL East title since 2012 is 17. Any combination of Yankees wins and Rays losses would give the Yankees the title.

Beginning Friday night at Yankee Stadium, where the Yankees open a three-game series against the resilient A’s, it will be all about hosting up to four games in an ALCS should they win a best-of-five ALDS. That’s something they are in a very strong position to do since the top two teams in the AL earn that right to play the team with the third-best record and the wild-card game winner.

The Yankees, who have the AL’s second best home record at 49-20, are 88-47 and running away with the division. The AL West-leading Astros, with baseball’s best home record at 51-17, are a game behind at 87-48.

Of course, playing four of seven ALCS games at home doesn’t guarantee a ticket to the World Series. However, what happened in the 2017 ALCS between the Yankees and Astros, the top two teams this time around, is still fresh.

The Astros won the first two games in Houston and the Yankees took the next three at home. Needing to win one of two games in Houston to reach the World Series for the first time since 2009, the Yankees watched the Astros batter Luis Severino in Game 6 and win Game 7, 4-0. In the four games in Texas the Yankees scored a total of three runs.

Shortly after that series ended, Hal Steinbrenner and Brian Cashman dismissed Joe Girardi as manager and replaced him with Aaron Boone, whose first team beat the A’s in last year’s AL wild-card game and then got smothered by the eventual World Series champion Red Sox.

So with the AL East title locked up, the focus is on remaining healthy and ensuring that four of a possible seven-game ALCS are played in The Bronx.

“We want to keep winning, that’s big,’’ Aaron Judge said prior to the Yankees posting a 5-4 West Coast road trip that opened 0-3 in Oakland and included taking two of three from the Dodgers and sweeping three from the Mariners. “We know how rowdy [Yankee Stadium] gets in the postseason and how crazy these fans are. We have to keep winning to make sure we keep that home-field advantage for the postseason.’’

Speaking this past week about not letting up, Boone made it very clear that thought hasn’t invaded his club, which hasn’t let up on the gas even though it has been in position to win the AL East since stretching its lead to 10 lengths on July 20.

“I think our guys have done that really well all season long,’’ Boone said. “I believe the strengths of this team from a makeup standpoint, is their ability to bring it every day.’’

And there might be some big names helping the cause who haven’t contributed so far. Boone believes outfielder Giancarlo Stanton (nine games all year) will come off the injured list. Ditto for Dellin Betances and Luis Severino (combined zero games). Boone believes center fielder Aaron Hicks will return, too.

Also of some assistance will be the roster expanding beyond 25 on Sunday. That will allow the Yankees to give 17-game winner Domingo German a chance to alter his workload and provide more bullpen arms for Boone.