It might be as soon as Monday or late October when Game 7 of the World Series is played.

Whenever the last out of the Yankees’ season is made, the nature of a relationship between two men from the opposite end of baseball’s universe will undergo a severe change but it won’t end.

No longer will Brett Gardner and CC Sabathia, after 11 seasons together in pinstripes, be teammates who occupy lockers on each side of the entrance to the inner sanctum of the Yankees’ clubhouse.

Gardner, 36, is eligible for free agency following the season and wants to continue a career that has exceeded expectations since it began. Sabathia, 39, is headed for retirement on the way to the Hall of Fame.

Sabathia, who grew into a 6-foot-7 and 300-pound stud pitcher, was a first-round pick (20th overall) by the Indians in 1998 out of high school in California. Seven years later, Gardner, now 5-foot-11 and 195 pounds, walked on at the College of Charleston and willed himself into a third-round pick of the Yankees in 2005.

Sabathia arrived in the Bronx via a seven-year, $161 million free agent contract in 2009, when Gardner was attempting to survive in the big leagues after playing in 42 games the year before.

Sabathia has made $260 million; Gardner $72 million.

Sabathia grew up in Vallejo, California, a town of 116,000 in the Bay Area that covers 49.5 square miles. Gardner was raised and still resides in Holly Hill, South Carolina, with a population of 1,281 and encompasses just 1.45 square miles.

Beginning Friday night at Yankee Stadium they will attempt to help the Yankees beat the Twins in the best-of-five ALDS and advance to the ALCS.

Pitchers and hitters don’t often become friends, but Sabathia and Gardner did. They are clubhouse leaders; their families are close enough to spend holidays together and each is the other’s target of abuse.

Sitting side by side in a small room behind the T-Mobile Park visitors’ dugout in Seattle in late August, Sabathia and Gardner spoke about what each has meant to the other and offered proof differences can attract instead of separate.

“I think it did. We have all those things not in common but we have one thing in common and that is to try and win baseball games. Try to be the best teammate and best player on the field,’’ Sabathia said. “No matter where you are from or what background you grew up in you can relate to somebody who has the same type of drive — willing to win and kick somebody’s ass every time out there. He is one of the toughest guys I have ever seen play the game. We don’t have a lot in common but we have a lot in common.’’

According to Gardner, their differences are pronounced, but winning trumps all of them.

“You could run down a whole list of things we don’t have in common or differences where we grew up. Like ‘C’ said a lot things we do have in common and one of the most important things we do have in common as far as being part of the team we are working toward one common goal,’’ Gardner said. “All the work he has put in long before I thought this dream of mine was going to become a reality, it all comes to a point that we are all doing it for one reason.

“The friendship we have serves as an example not just for guys on our team, but one of the great things about the game of baseball is guys from all over the world, not just from small-town South Carolina or Vallejo, California. … CC is going to play 19 years and I might play for 12 or 13 years, whatever it might be. Hopefully we have formed relationships that are going to last a whole lot longer than that. … … Even if ‘C’ wasn’t sitting here, he is probably the best teammate I have played with. A big part of that is the way he took me in as a young player early in 2009 and showed me that, even if we have a whole lot of differences we got a lot of things in common and formed a special friendship that I will cherish forever.’’

When Sabathia joined the Yankees he arrived not knowing much about Gardner, but they hit it off quickly.

“When I got here he was fighting for the spot in center field and we got super close that first year by hanging out a lot — after games, dinner. A.J. [Burnett] was here, [Nick Swisher] was here, [David Robertson] would hang with us. … We had a good group of guys who would hang out off the field and our friendship grew from that,’’ Sabathia recalled.

Since Sabathia was an established star, Gardner knew more about the pitcher than the pitcher did of the spare outfielder.

“In 2008 I had my first taste of the big leagues and in the offseason we made all those big moves and he was right there at the top with [Mark Teixeira]. … Had never met him before and we quickly became close,’’ Gardner said. “A couple of his kids are the same age as my two kids and sometimes we get together for holidays — Fourth of July, Memorial Day, Easter and pool parties.’’

The pesky leadoff hitter with pop and the once-power pitcher turned finesse artist in the late stages of his terrific career have never faced each other.

So, how would that go?

“I don’t know,’’ Sabathia says after a signature loud laugh. “I know he would be crying about my strikes.’’

Sabathia dislikes hitters bunting against him. So, of course, that would be Gardner’s approach in the lefty-versus-lefty matchup.

“I would try to bunt and piss him off. He would probably hit me and I would go to first base,’’ Gardner said with a straight face.

Sabathia plans to stay in New Jersey so he will be around the area. Gardner will be a free agent, but played every day in center field when Aaron Hicks went down in early August with a flexor tendon problem in his right elbow. He finished with a .251 batting average and career highs in OPS (.829), home runs (28) and RBIs (74). With Hicks’ health history, Jacoby Ellsbury not having played since 2017 and prospect Estevan Florial a ways away from the big leagues, the Yankees may have a need for Gardner in 2020.

Should Gardner return, and it is difficult to envision him in a different uniform, the relationship should continue.

“I think it will. This is way deeper than baseball at this point. You always have a few guys you play with you keep in touch with — from my Indians years, Milwaukee, here with the Yankees — but he is the closest since being around each other for so long and being around the families,’’ Sabathia said.

First, the duo wants another trip up Lower Broadway as World Series champions, completing what they feel is unfinished business.

“CC’s first season in New York was my first full season and I didn’t play a big part in that. But you kind of take it for granted, figure that we are going to be there every year because that is what the expectations are. The reality is there are a lot of good teams in the American League fighting for the same thing we are fighting for. It’s been a long time coming, it has definitely been way too long,’’ Gardner said.

Sabathia dragged his damaged right knee back for one more chance at a title to erase the bitter taste of losing to the Astros in seven games in the 2017 ALCS, when the Yankees lost despite leading the series 3-2.

“I feel like it is unfinished business from ’17. Being with this group of guys is the reason I wanted to come back this year. I felt we really had a good group of guys. I know this group of Yankees is going to win the World Series, [Aaron] Judge, Gleyber [Torres], Gardy, so I wanted to be here and cherry pick one more [title] with these guys because I know they are so close and definitely going to win,’’ Sabathia said.

Asked who will be on the receiving end of his barbs with Sabathia gone, Gardner’s answer was quick.

“I already give Judge a lot of heat. I don’t know if I can turn that up. I am always up for giving Aaron Hicks a hard time and deservedly so, and we enjoy getting on each other,’’ Gardner said.

And Sabathia?

“My kids. It is time for me to be home and be with the family full time. I love being around here, my teammates, but it is time for my old ass to be around my family,’’ Sabathia said.

They have plans to someday fish together in Costa Rica, fully aware 11 seasons together in pinstripes have not only been highlighted by winning baseball games but also serve as proof differences can not only spawn a relationship but cause it to flourish.