New York Yankees slugger Aaron Judge will miss an extensive period of time after straining his oblique against the Kansas City Royals Sunday afternoon.

NEW YORK — Aaron Judge won’t be back with the New York Yankees anytime soon, a further blow to an injury-decimated team with a mediocre record 3½ weeks into the season.

New York’s biggest offensive threat and the heart of its clubhouse went on the injured list for the third time in four seasons Sunday, a day after straining the oblique muscle on the left side of his abdomen while hitting a sixth-inning single against Kansas City.

“Especially tough times like this, when a lot of guys are beat up, I wanted to be out there in the trenches with the guys every single day,” Judge said after Sunday’s 7-6, 10-inning win over Kansas City .

Manager Aaron Boone called it a “pretty significant strain in there” and would not estimate a return date. Judge broke his right wrist when hit by a pitch by the Royals’ Jakob Junis last July 26, and while Boone originally projected a return in three weeks, Judge did not rejoin the Yankees until Sept. 14.

“There’s no need to put a time, a clock on it, because what happened — just like what I did with the wrist last year,” Judge said. “So no need to go down that road again.”

New York was 65-36 when Judge went on the DL, went 25-20 while he was out, then won 10 of its final 16 games en route to a second-place finish in the AL East. The Yankees are 11-10 this year.

Asked whether he felt anything before the sixth-inning single, Judge paused three seconds before answering: “just on the swing.” Asked what his first thought was when he felt the pain, he responded to the surrounding media: “I can’t say that on TV. It wasn’t good.”

Judge became the Yankees’ major league-high 13th player on the injured list and the 14th overall this season, joining left fielder Giancarlo Stanton (strained left biceps), center fielder Aaron Hicks (strained left lower back), catcher Gary Sanchez (strained left calf), shortstop Didi Gregorius (Tommy John surgery), third baseman Miguel Andujar (torn labrum in right shoulder) and first baseman Greg Bird (torn plantar fascia in left foot).

Those six and Judge accounted for 175 of the team’s record 267 homers last year, 515 of 851 runs and 515 of the 821 RBIs. In addition, new shortstop Troy Tulowitzki has a strained left calf.

New York’s starting lineup for the series finale against the Royals would have pushed the spring training rule requiring four regulars to make the trip for road games, resembling a Broadway show stocked with understudies near the end of a lengthy run.

“You feel like this a great opportunity for us,” Boone said. “I feel like it can make the end all that much more sweet.”

DJ LeMahieu was at second, followed by designated hitter Luke Voit, center fielder Brett Gardner, right fielder Clint Frazier, left fielder Mike Tauchman, third baseman Gio Urshela, first baseman Mike Ford, catcher Austin Romine and shortstop Tyler Wade. New York gave second baseman Gleyber Torres a day off, leaving Gardner and Voit as the only starters left from opening day.

“They’re going to be just fine,” Judge said. “Other guys get a chance to get some playing time and get a chance to show what they’ve got and step up.”