Lehigh Valley manager Ted Plessl stresses to his reserves to take their roles seriously.

The reason is simple: No one knows for sure when they might be needed.

On Saturday afternoon — for the second consecutive game — Plessl had to rely on one of his substitutes to fill a void. And for a second straight time, that player came up huge.

This time, it was Northwestern’s Nick Henry who got the call and came up clutch in a 3-2 victory over Berks County at UYA Ashburn and Showcase Fields. With the win, Lehigh Valley has now reached the Carpenter Cup semifinals for the first time since 2013.

“We always tell our alternates if they come to the game, we’ll try to get them in the dugout and they should be prepared to play in case we need them,” said Plessl, who found out two minutes before the game that one of his LV players couldn’t play.

“I said to Henry, ‘Nick, please tell me you have game pants here and you have your equipment.’ And he said yes. I had to sign a replacement sheet for him, and get it up to the press box so he could play.”

And play he did.

With Lehigh Valley trailing 2-1, Stroudsburg’s Braden Breithaupt led off the ninth inning with a single. After Liberty’s Ben Piripavel laid down a bunt to advance Breithaupt to second, Henry delivered an RBI single to tie the game. The Northwestern product then raced to third on a hit-and-run single off the bat of Emmaus’ Brandon Robinson, whose grounder ended up going right where the shortstop would have been had he not been covering second base.

Henry came home with the eventual game-winning run on a sacrifice fly by Stroudsburg’s Ben Stokes.

“We always say to the kids, ‘If you’re an alternate, don’t take that position too lightly because we just don’t hand out alternate positions to anybody,’” Plessl said. “We have nine alternates. We try to have alternates that are outfielders, infielders, catchers and pitchers so we’re covered just in case something happens.”

While Henry played a pivotal role on offense, it was Northwestern’s Carter Welch and Pleasant Valley’s Dan McEvoy who delivered on the mound.

The two were part of a foursome that held Berks County in check for most of the game.

After starter Evan Zwolenik allowed two first-inning runs, the LV staff pitched shutout ball the rest of the way.

Welch, who earned the victory, entered the contest in the seventh and provided a 1-2-3 inning.

In the eighth, Welch got a little help from his Northwestern teammates. Shortstop Rafe Perich started a 6-4-3 double play, which ended with Derek Holmes at first.

“That double play was huge since we couldn’t afford to give up another run,” said Plessl. “Welch threw really well.”

McEvoy closed the door on Berks County in the bottom of the ninth. The Pleasant Valley hurler retired the side in order, including a pair of strikeouts, to gain the save.

“He’s one of the best pitchers in the EPC (Eastern Pennsylvania Conference),” said Plessl. “He just did the job. He struck out the last two batters to preserve the victory, and now we’re going to the semis.”

Lehigh Valley was scheduled to face Delaware South at 1 p.m. today at Citizens Bank Park with the winner advancing to Tuesday’s championship game.

“Historically, we’ve had success down there,” said Plessl. “When (a Phillies representative) was telling the kids about going to the ‘Bank’ and explaining to them what kind of shoes they have to wear and other information, he was saying 2013 was your last time there ... and that the Lehigh Valley has great history in this tournament.”

FIVE IS ENOUGH … Lehigh Valley recorded five hits in the game, all of which were singles. Parkland’s Blake Barthol and Jeremy Piatkiewicz, along with Robinson, Breithaupt and Henry, recorded the basehits.

FIRST LV RUN ... After Berks grabbed its 2-0 lead, LV cut the deficit in half with a run in the fourth. Singles by Barthol and Salisbury’s Quinn Warmkessel, along with an error, produced the run.

WHO’S TURN NEXT? … It must be good to be an alternate for Lehigh Valley. On Wednesday, Central Catholic’s Brian Horoshko got the call and came through with three hits and three RBIs. On Saturday, it was Henry who delivered.

Lehigh Valley 000 100 002 - 3 5 0

Berks County 200 000 000 - 2 7 1

Zwolenik, Gustofson (4), Welch (7), McEvoy (9) and Greenzweig, Transue (5); Book, Leverington (4), Laraia (6), Duffie (7), Renner (9) and Rodriguez, Vanderslice (5). W - Welch. L - Renner. S - McEvoy.