CLEVELAND — The Yankees traded for Mark Leiter Jr. in July with October in mind.
But the right-hander spent the ALDS watching, left off the roster, and he began the ALCS in the same spot.
“That’s not my choice,” Leiter said after Friday’s 8-6 Game 4 win over Cleveland in the ALCS. “When you get a chance, you have to take advantage of it.”
And the right-hander got that chance Friday when he replaced the injured Ian Hamilton (calf) on the roster and made his postseason debut in the bottom of the seventh.
“[Aaron Boone] kept telling me to be ready for anything and there was a chance I’d be used to get big outs,’’ Leiter said. “So I stayed ready.”
He gave up the tying run in the bottom of the eighth but got five outs in the game and picked up the victory when the Yankees scored a pair of runs in the top of the ninth.
Not bad for his first game since the regular season ended on Sept. 29.
“I tried to keep it as routine as possible,’’ Leiter said. “It was rowdier warming up, but I stayed in the right mindset: just make pitches. That’s generally done me well in big moments.”
Leiter had never made the playoffs before, but his uncle, Al, is a World Series champion and Leiter saw his father, Mark Sr., miss out on the playoffs during an 11-year major league career.
“Watching it my whole life, I know it doesn’t matter what happens,’’ Leiter said. “You have to be ready for the next play. That’s the way it felt.”
Acquired from the Cubs prior to the trade deadline, Leiter pitched poorly enough afterward that he was excluded from the roster for the ALDS against the Royals and this ALCS.
Leiter came in after Clay Holmes faltered for a second straight night.
After an impressive effort to get out of the bottom of the seventh, Leiter gave up the lead in the eighth.
The right-hander allowed a leadoff double to Bo Naylor and a grounder that sent Naylor to third.
A pop-up by Steven Kwan put Leiter in position to get out of the inning unscathed, but the pitcher mishandled a slow grounder by David Fry and then his toss to first got by Anthony Rizzo, allowing Fry to reach — and Naylor to score the tying run.
But the Yankees took the lead in the top of the ninth.
Tommy Kahnle finished an eventful night for the pen and the Yankees by tossing a scoreless ninth for the save.
“It did get hairy,’’ Kahnle said.
Leiter bailed out Holmes, as Boone summoned him with runners on first and second and one out in the seventh in a one-run game.
Follow The Post’s coverage of the Yankees in the postseason:
- Yankees on verge of World Series after closer’s latest meltdown
- Sherman: How Aaron Boone somehow got worn out Yankees to 27 outs
- Brutal camera work gave Yankees fans everywhere a Game 4 panic attack
- Reliever’s first day back with Yankees was a heart-stopping adventure
Leiter got one of Thursday’s heroes, pinch hitter Jhonkensy Noel, to fly out to deep left before Andres Gimenez struck out.
General manager Brian Cashman said before the game the Yankees hoped Leiter and his split-fingered fastball would be an effective pitch against Cleveland’s lefty-heavy lineup, making Leiter the choice over other candidates like the inexperienced Cody Poteet and Clayton Beeter.
“He’s had a hell of a year, just not as good [after] he got here for us,” Cashman said of Leiter, who had a WHIP of 1.101 in 36 ¹/₃ innings as a Cub this season and a 1.708 WHIP in 21 ²/₃ innings with the Yankees.
“But he’s certainly capable,’’ Cashman said. “He’s got a pretty good weapon against left-handed hitters. I hope it benefits us. Hopefully when called upon, he’ll give us quality outs.”
He got off to a good start Friday.
