Carlos Rodon of the Yankees reacts during the fourth inning against...

Carlos Rodon of the Yankees reacts during the fourth inning against the Kansas City Royals in Game 2 of the ALDS at Yankee Stadium on Monday. Credit: Jim McIsaac

They jammed Yankee Stadium for Game 2 of the ALDS on Monday night, 48,034 strong, and cheered on Carlos Rodon in a way he’s never been cheered on in the Bronx before.

They wanted to believe in Rodon.

But after a rip-roaring start, Rodon was charged with four runs in the fourth and was gone. The lefthander took the loss as the Royals evened the series with a 4-2 victory.

Boy, did Rodon come out firing. First batter: Strikeout. Second batter: strikeout. Third batter: strikeout. Twelve pitches, 10 strikes.

This version of Yankee Stadium has hardly been louder.

“It’s a pretty cool experience to be able to pitch a playoff game in Yankee Stadium,” said Rodon, who struck out five of the first eight batters to face him. “We had some great energy today.”

But Rodon started to show cracks in the third inning, which ended with a vicious line drive by Vinnie Pasquantino to Juan Soto in right with two men on.

And with the Yankees holding a 1-0 lead, thanks to Giancarlo Stanton’s two-out RBI single in the third, Rodon fell apart in the fourth.

Suddenly, the strike zone eluded Rodon. Fastballs that had dotted the corners now were going way high. Sliders that once had bite in the zone now were bouncing in the dirt.

Five of the first six pitches Rodon threw in the fourth were balls. The one that wasn’t — a 2-and-0 slider to Salvador Perez — ended up going 402 feet into the leftfield seats to tie the score.

Then the dam broke.

Yuli Gurriel singled. Rodon bounced a wild pitch before striking out Michael Massey. Tommy Pham singled to center to give Kansas City the lead. Pham stole second. Hunter Renfroe struck out, Rodon’s seventh and final K. No. 9 batter Garrett Hampson singled to make it 3-1 and took second on the throw home.

Manager Aaron Boone took the slow walk to the mound and removed Rodon. Ian Hamilton gave up an RBI single to Maikel Garcia to make it 4-1 and close the book on Rodon.

Rodon was charged with four runs in 3 2⁄3 innings. He gave up seven hits — four of them in the fourth — and did not walk a batter. He threw 72 pitches.

He was great, and then he was not, and then he was gone.

“I left some sliders up in the zone — not up in the zone — but hittable sliders that they made some good swings on,” Rodon said. “I think I could have been better with those pitches. Bury those sliders. It’s just unfortunate. I want to be better than that.”

It was Rodon’s second postseason start. In his first one, for the White Sox in the 2021 ALDS vs. Houston, he allowed two runs in 2 2⁄3 innings in Chicago’s 10-1 defeat.

This was better, especially early, when Rodon’s fastball was crisp and his breaking stuff was true.

Why did he falter? Could the massive adrenaline rush of Rodon’s first Yankees postseason outing have worn off after the first couple of innings?

Before Monday’s game, catcher Austin Wells talked about how amped up Rodon was. It was more than 2 1⁄2 hours before Rodon threw the first pitch, a 97-mph fastball.

“I think he’s going to be really excited,” Wells said. “I know he already is. I was just talking to him before coming up here and talking about hitters, and he’s pretty fired up.”

Said Rodon: “I wouldn’t say I tired out. I’ve just got to be better with those pitches, just more fine with them, and get to better spots.”

It could be that the Royals are no pushover, as the Yankees learned in their hard-fought 6-5 victory in Game 1.

The 106-loss team from a year ago made the playoffs as a wild card with 86 wins and then swept the Orioles in the Wild Card Series.

Gerrit Cole wasn’t great in Game 1, allowing three runs in five innings-plus. But the Yankees won the back-and-forth battle, which included five lead changes, an MLB postseason record.

Rodon’s toughness was on display in the third inning when Garcia lined a ball off his glove that went for a single. Rodon retrieved the ball behind the mound and fired off-balance to first, but Garcia beat it out.

Boone and Yankees trainer Tim Lentych started out to check on Rodon. He waved them off to go back to the dugout.

Back they went.

If this series goes the distance, back Rodon will go — to the mound. He’s in line to start the deciding Game 5 in the Bronx.

The fans will turn out. They will cheer on Rodon. They again will want to believe in him.

But will they be able to?