“He wasn’t getting up,” Yankees first baseman Mark Teixeira said of Derek Jeter. “So you knew something was wrong.” (RAY STUBBLEBINE/REUTERS)

In his 18 seasons wearing pinstripes, Derek Jeter has played in more postseason games than anyone in baseball history, 158 in all, essentially another season tacked onto his illustrious career.

As the New York Yankees try to return to the World Series, they’ll be without their iconic shortstop, who fractured his ankle in the 12th inning of Game 1 of the American League Championship Series.

“When you think about postseason baseball,” Tigers Manager Jim Leyland said Sunday, “I guess the Atlanta Braves’ 14 straight postseasons, Reggie Jackson, Mr. October — and Derek Jeter. I mean, if I said ‘postseason baseball,’ what do you think about? . . . So it’s really an unfortunate situation, it really is.”

As the Yankees took batting practice before Game 2 Sunday afternoon, Jeter was undergoing more tests to determine the full extent of the injury. The team announced that an MRI exam and CT scan conducted Sunday confirmed the fracture; Jeter is wearing a splint and is on crutches. He was not at Yankee Stadium for Game 2 and will not be able to travel with the team to Detroit for Game 3. Recovery is expected to take three months.

After the Tigers’ go-ahead run crossed the plate in the 12th inning of Game 1, Jeter fielded a sharp grounder off the bat of Jhonny Peralta, falling awkwardly to the ground and grimacing in pain.

“He wasn’t moving. He wasn’t getting up,” said Yankees first baseman Mark Teixeira. “So you knew something was wrong.”

When Jeter was finally helped to his feet, he was unable to put any pressure on the ankle. He had to be helped off the field by Yankees Manager Joe Girardi and team trainer Steve Donahue. “He’s as tough as they come,” said General Manager Brian Cashman. “So when you see that, you know it’s serious.”

The Yankees shuffled their lineup heading into Game 2. Jayson Nix replaced Jeter at shortstop and batted eighth. Girardi opted to lead off with Ichiro Suzuki, hitting Robinson Cano second and sliding Raul Ibanez into the clean-up spot.

“We have to find a way,” Girardi said.

Jeter finished the postseason 9 for 27 with two RBI and 10 strikeouts.

Tigers notes: Despite winning the series opener, Leyland had some lineup shuffling of his own to contend with Sunday. Entering Game 2, Detroit reliever Jose Valverde was responsible for the last seven runs given up by the Tigers, including four in the ninth inning Saturday that forced extra innings.

Leyland said Valverde would not be called on to close Game 2 but the veteran manager wasn’t ready to strip the three-time all-star of his closing duties.

“I guess that sounds like I’m mud wrestling, but I am really not,” Leyland said. “I still consider him the closer, but he will not close the game.”

Leyland chose his words carefully. While he said coaches will work on Valverde’s mechanics, confidence also appears to be a concern.

Leyland wasn’t sure when Valverde might close again, but for the time being, the Detroit manager will turn to a committee that includes right-handers Joaquin Benoit and Octavio Dotel, and left-hander Phil Coke.

Valverde had 35 saves this season. After successfully closing Game 1 of the American League Division Series against Oakland, he blew the save in Game 3, allowing three runs in two-thirds of an inning and taking the loss.

“You can’t pitch with 10 pitchers in the postseason,” Leyland said. “So Jose Valverde will be a very important part of this postseason. If he’s not, it’s going to be tougher for us, obviously.”