MLB

PUMP ‘EM UP

JOBA Chamberlain threw all of 24 innings last year and received one of the biggest ovations during introductions.

When he came on for the eighth inning, the 55,112 in the house chanted his name. When he threw his first pitch, camera flashes lit up the Yankee Stadium night.

A ground-out to second produced an explosion of sound. When his 3-2 slider buckled Alex Rios, but was called ball four, the crowd booed.

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Another slider froze Vernon Wells for strike three for the second out as Rios stole second. Following a mound conference with Alex Rodriguez, Derek Jeter and Jorge Posada, he went right after Frank Thomas, getting ahead 0-2 then busting a 97-mph fastball past one of the greatest sluggers the game has produced.

This is why Chamberlain is in the bullpen. The plan is working.

This is why Joba is not in the starting rotation and his performance was a major reason the Yankees came away with a dramatic, 3-2 victory over the Blue Jays and made Joe Girardi a winner his first game as Yankees manager.

Chamberlain sliced through the heart of the Blue Jays tough lineup and came away doing his trademark 360 pump celebration.

“Oh my gosh,” is all teammate and fellow rookie Ian Kennedy could say after the performance and pump.

“That was a good one,” Chamberlain acknowledged.

On this night there were no midges to get in Joba’s way. And watching it all was his dad, Harlan.

This is what Opening Night is all about. The Yankees plan for success under Girardi goes something like this: Pitching, defense, battle every at-bat, run the bases hard, then come the final six key letters of the plan – Joba-Mo.

What a weapon – 21 pitches for Joba, 12 for Mariano Rivera.

“My job is to get the ball to Mo,” Chamberlain said, putting it all in perspective.

And to light up the night. Rivera came on for the save in the ninth. He got a strikeout, a flyout then a ground out to second from Marco Scutaro.

Then Frank Sinatra sang.

That was the same Scutaro who blasted a walk-off homer off Rivera last year. This is a new year, and the Yankees played with the kind of energy that promises to be a trademark of the Girardi Era. They played quickly, all it took was 2 hours and 31 minutes, but that’s what happens when you get great pitching from Chien-Ming Wang and Joba-Mo.

What did Hank Steinbrenner like best about the night.

“The bullpen,” he said. “The big two, Joba and Mariano.”

I’m with Hank on that one.

This is what the Yankees want to do in this new version of Joba Rules when Chamberlain is allowed to pitch on successive nights. Don’t think he’s not pumped about the chance to come back tonight.

“It is exciting to know that you can put your spikes on [tonight],” Chamberlain said. “Hopefully I can get the opportunity to pitch and do some things better that I didn’t do tonight.”

So what do you need to do better, Joba?

“I need to eliminate some pitches,” he said. “I just have to keep attacking the zone.”

A year ago at this time, Chamberlain was rehabbing in Tampa, and no one knew who he was or the thunder that would come from his right arm.

“This is a lot better than rehab,” he said with a smile. It sure is. And the Yankees are a much different and better team with Joba-Mo.

Don’t forget Chamberlain is only 22 and now has 25 major league innings under his belt. He’s still learning, so when Thomas came to the plate with the tying run on second, Rodriguez, Jeter and Posada came to the mound to basically take his temperature.

“They do a great job of settling people down,” Joba said. “It’s tremendous to have all that. We have a lot of great arms in the bullpen, it would be a shame for us to give it up because our starters do a great job.”

Joba-Mo can close the door.

kevin.kernan@nypost.com

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