FORT MYERS, Fla. – David Ortiz watched the Red Sox honor Mariano Rivera on his last trip to Fenway Park. He was there to see Derek Jeter make his final appearance in Boston.

The Red Sox-Yankees rivalry is the best, the most emotional, the biggest of them all.

The 2016 season is Ortiz’s final lap as a player. He knows the drill. He doesn’t want treasure. He doesn’t need another painting. Save the rocking chair for someone else.

When Ortiz, 40, makes his final Yankee Stadium appearance on Sept. 29, this is what he wants, and it speaks volumes about Ortiz the player, the competitor, the enemy, the star.

“You know what I want most of all?’’ Big Papi told The Post on Tuesday at JetBlue Park. “I would love it if the fans at Yankee Stadium gave me a standing ovation.’’

That’s what he wants, and that would be the perfect tribute to Ortiz, who owns 503 home runs.

Yes, Big Papi broke the hearts of Yankees fans everywhere when he led the Red Sox to that historic comeback in 2004. The Yankees had the Red Sox dead and buried with a 3-0 lead in the ALCS.

Roles were reversed. The Curse of the Bambino came to an abrupt end, thanks to the Red Sox’s new Bambino, Big Papi, who earned ALCS MVP honors.

Boston staged the greatest comeback of them all, propelling them to their first World Series victory since 1918. That started it all for Papi and the Red Sox.

“The Yankees were the team to beat back then,’’ Ortiz said when I asked him what that comeback did for him. “Being able to do what we did was something that was very special. It was career-lifting for me. People get to know you better, focus on you a little more. If you continue to be successful, you can build a career out of it.’’

You sure can. When he first arrived in Boston, Ortiz was a part-time player. The power had not developed in the Twins organization, where he was taught to spray the ball. When he first came over, teammates jokingly called him Juan Pierre because he was such was a spray hitter.

It wasn’t long before he became Big Papi.

Since 2004, the Red Sox own three World Series titles; the Yankees have one.

Yankees fans can show class by sending off Ortiz with a standing ovation — even those fans who somehow manage to make their way into premium seat locations at less than full price.

With the fans honoring Ortiz, the Yankees don’t have to spend much on a parting gift. The Yankees can save that money for Bryce Harper down the free agent road.

The precedent has been set, too.

There was no more hated rival in New York than the Pacers’ Reggie Miller, yet in Miller’s last appearance at the Garden in 2005, fans cheered and chanted: “Reg-gie! Reg-gie!’’

Miller even gave Spike Lee a hug that day.

Yankee fans should chant: “Pa-pi! Pa-pi!’’ and give him that standing ovation.

The Yankees have been tortured by Ortiz through the years. There is still a jagged hole in the concrete in the bowels of the Stadium behind home plate where the Yankees dug up an Ortiz jersey in 2008 that was buried there during construction by a Red Sox fan.

Ortiz likes this Red Sox team, even though Pablo Sandoval is sporting a big belly and Hanley Ramirez is trying to show he can play first base. Ortiz said he is hoping to go out with a “crown.’’

Big Papi says this team has better balance than recent Red Sox teams and the acquisition of David Price is huge.

“We need a guy like him,’’ Ortiz said of Price, a pitcher he has feuded with in the past. “We need an ace. They brought him in to try and win a championship here. In my case, I’m going to be his No. 1 supporter.’’

Ortiz deeply respects the fans, even those from other teams who boo him, because it shows how much they love the game and their team. Yankees fans can show Ortiz respect in that final game.

Cheer for Big Papi. Chant his nickname. Send him out with class.