The bullpen gate swung open, the music blared and Mariano Rivera entered the game in the ninth inning to another long standing ovation.

Only this was at Fenway Park. A Yankee receiving a standing ovation at the Green Monster, imagine that.

On this sweaty baseball evening, Fenway Park became the Green Mo. Let the love flow as a sellout crowd of 37,601 fans stood and cheered Rivera.

What a sight it was to see. But that’s what happens when you are baseball royalty, the classiest player in the game in your final season.

The world loves you and you love them back — even Red Sox Nation.

As you watched and listened you realized there is much more than a baseball lesson here for the world we live in today. Class can lead the way, if we demand it of ourselves and others, if we simply follow the Lessons of Mo.

“I always love to pitch here,’’ Rivera said in the cramped visitor’s clubhouse, saying he was focusing only on the job at hand. “Yankee Stadium is home, but I love coming here, it’s a great game here. I don’t want to be rude, but I didn’t pay attention. It has always been hard ballgames here. I respect the organization, I respect the fans. That’s why I give it back.’’

Rivera, 43, got the job done, of course, notching his 31st save of the season and the 639th of his career. Coming off the eighth-inning All-Star lovefest at Citi Field on Tuesday, this has been some week for Rivera.

He got David Ortiz to pop up, and after a bloop single to right by Mike Carp, Rivera struck out Jonny Gomes and Jarrod Saltalamacchia.

Catcher Chris Stewart immediately fired the final pitch back to Rivera for the closer’s massive trophy case and the Yankees’ 5-2 win over the Red Sox was preserved, a win that snapped a three-game losing streak.

Only the entry music was different this time. Instead of “Enter Sandman,’’ the Red Sox played Twisted Sister’s “We’re Not Gonna Take It.’’

Well, they took it again. Rivera has saved his past 12 straight games at Fenway, dating back to June 3, 2007. He owns 35 regular-season saves here.

The Red Sox fans gave Rivera an ovation the Yankees first game here in 2005 as he was introduced after the Red Sox’s world championship banner was raised. Boston fans were having some fun after the Boston heroics in the 2004 ALCS against Rivera.