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The Major League Baseball season opens Sunday when the St. Louis Cardinals visit the Pittsburgh Pirates – the first of three games on the schedule that day.

While there are many story lines that are bound to dominate the season – will the Kansas City Royals repeat their World Series title? Can the young New York Mets pitchers stay healthy? – none is likely to be more compelling than the farewell tours for two of the greatest sluggers of their generation and icons of the fiercest rivalry in baseball, David Ortiz of the Boston Red Sox and Alex Rodriguez of the New York Yankees.

Big Papi will be hanging up his spikes after this season while A-Rod intends to do so after 2017, and the way the two players announced their decisions and handled the media scrum that followed speaks volumes about each of them.

Ortiz is a big personality who has made himself beloved in Boston through clutch hitting and timely passion, too – bringing the city together after the disaster of the Boston Marathon bombing by growling “This is our f---ing city” at a Fenway Park memorial to the victims of attack.

Big Papi, who will undoubtedly receive the same sort of farewell tour that his Yankee rivals Derek Jeter and Mariano Rivera had in recent years, told the world about his decision to retire on his 40th birthday last November in a thoughtful video announcement that was posted on Jeter’s Players' Tribune website.

He said that while he was “ready to experience the next [chapter] in my life,” he was “really proud of what I’ve accomplished over the years.”

A-Rod blurted out to an ESPN.com reporter last month that he planned to retire after his current contract with the Yankees expired at the end of 2017.

“I’ve really enjoyed my time,” he said. “For me, it is time to go home and be Dad.’’

Or maybe not. The next day the Yankee designated hitter began to backtrack under questioning by reporters, saying that he might change his mind – possibly if Barry Bonds’ all-time home run mark of 762 were within his reach.

“There is no plan,” A-Rod told reporters. “I have a contract, and I’m going to fulfill that commitment … I’m 40 years old. I’ve had two hip surgeries. At my age, I’m day-to-day.”

By contrast, in a December video conference hosted by the Players’ Tribune – the first public event after Ortiz announced his retirement – Fox News Latino asked Big Papi if there was any chance he would change his mind.

“You never know how things turn out,” he answered, “but I’m very sure about what I’m doing.”

“I took my time to make this decision,” he added. “I’m at peace with it, and I’m going to enjoy next year.” Nothing he’s said since indicates otherwise.

Both players had healthy and productive seasons in 2015. After a full year suspension for his involvement in the Biogenesis Clinic scandal, Rodriguez rebounded by hitting .250 with an impressive 33 home runs with 86 runs batted in. Ortiz showed no signs of aging, hitting .273 with 37 homers and 108 RBI.

While fans across the big leagues will get the chance to say goodbye to Ortiz, most of the attention this year in regards to A-Rod is sure to focus on his closing in on the home run crown.

Rodriguez is No. 4 on the all-time list with 687, behind Bonds, Hank Aaron (755) and Babe Ruth (714). Another season like 2015, and A-Rod will move past Ruth; another two seasons with similar home run totals would leave him tantalizingly close to Aaron.

Ortiz has 503 homers, which puts him at No. 27 on the all-time list.

Both player’s career stats would have made them shoe-ins for the Hall of Fame in practically any other era. But both have been dogged by rumors of PED use.

Ortiz failed only one drug test – in 2003, when there was no steroids policy in place and the league was testing players, supposedly anonymously, to determine the extent of the abuse.

To date no player caught taking performance-enhancing drugs – or even alleged to have used them – has been voted into Cooperstown. Rodriguez, whose career has been littered with public-relations fiascos and squabbles with the media, seems unlikely to break that string.

But Ortiz might be able to, thanks to his leadership role in helping a formerly sad-sack franchise break the “Curse of the Bambino” and win three World Series between 2004 and 2013. If so, he would become only the third player born in the Dominican Republic to be enshrined in the Hall after Juan Marichal and Ortiz’s former Boston teammate, Pedro Martinez.

But Ortiz isn’t thinking that far ahead.

The Red Sox have finished last in American League East three of the last four years, and he’s hoping the changes the team made during the offseason – like signing pitcher David Price to a 7-year, $217 million deal – can fix that.

“We need a guy like him,” Ortiz said about Price. “We need an ace.”

And if he could ask for just one thing for the coming season?

“I would love it if the fans at Yankee Stadium gave me a standing ovation,” Ortiz said.