They are, without question, the two best fillies to race on dirt in this century.

They most likely would both appear on a Top 10 list of North America’s all-time greatest fillies or mares.

Their combined collection of wins includes such prestigious Grade 1 stakes as the Breeders’ Cup Classic, Preakness, Haskell, Breeders’ Cup Distaff and Kentucky Oaks.

They finished 1-2 in the balloting for 2009 Horse of the Years honors.

For two years, in 2009 and 2010, they represented the East and West and were the central figures in the sport’s most intense rivalry in decades.

Yet not even once did Rachel Alexandra and Zenyatta share the same starting gate, nor did they ever compete in a race that would have certainly become one of the most famous showdowns in the sport’s long history.

It was “The Rivalry That Never Was.”

“It was a very, very special time,” said Jerry Moss, who owned Zenyatta along with his ex-wife, Ann. “I haven’t seen anything else like what we saw in those years and the interest those two horses created. We always thought Zenyatta would face Rachel Alexandra but sadly it never did.”

In 2016, Rachel Alexandra and Zenyatta entered the National Museum of Racing and Hall of Fame together on the one day when the rabid fans of both great champions finally got to share common ground, and the connections of the horses strolled down memory lane to an unforgettable time for them and the sport.

“A highly emotional day,” said Barbara Banke, the widow of Jess Jackson, who bought controlling interest in Rachel Alexandra for his Stonestreet Stables after her amazing 20 ¼-length victory in the 2009 Kentucky Oaks. “It was a great time for us when ‘Rachel’ was racing."

Zenyatta (Eclipse Sportswire)

For all of the arguments the two horses sparked, there is surely no debate about their credentials being worthy of the Hall of Fame.

In a career that started in November 2007 and lasted through 2010, Zenyatta was practically perfect. Based in California, she earned $7.3 million and captured the imagination of racing fans by reeling off a mind-boggling 19 straight wins before she suffered a heart-breaking, career-ending loss by a head in the 2010 Breeders’ Cup Classic at Churchill Downs. A year earlier, the daughter of Street Cry captured the 2009 Breeders’ Cup Classic and her 13 Grade 1 wins included the Vanity and Lady’s Secret three times and Clement L. Hirsch and Apple Blossom twice (she also won the Hirsch once when it was a Grade 2 stakes) and the 2008 Breeders’ Cup Distaff (nee Ladies Classic).

“When you realize how difficult it is to win two or three races in a row, it’s really something what Zenyatta did,” said jockey Mike Smith, who rode Zenyatta in all but her first three starts. “When you get past five, it’s amazing. In her case, she was 19-for-19! Everything about her was special. She’s number one among fillies for me. How could she not be?”

Rachel Alexandra won only three of six starts at 2, but she blossomed the following year and assembled as good of a 3-year-old campaign as any filly has ever enjoyed.

In winning all eight of her 2009 starts, she obliterated her competition in the Kentucky Oaks and then, after Jackson purchased her, she became the first filly in 85 years to win the Preakness. She went on to capture the Mother Goose by 19 ¼ lengths before closing out the year with a victory in the Haskell over 3-year-old males, including Belmont Stakes winner Summer Bird, followed by a dramatic win against older males in the Grade 1 Woodward at Saratoga.

Rachel Alexandra won the Haskell during her 3-year-old season. (Eclipse Sportswire)

“Rachel Alexandra still has an extremely passionate fan base, and I think deservedly so,” said Steve Asmussen, who became the filly’s trainer after Jackson purchased her. “She exuded qualities that we all admire. There was an amazing amount of interest in anything you did with her, from the smallest of workouts, to a breeze, to race day. Every day brought out a tremendous amount of excitement to be around her. I was always amazed at how people wanted to lay their eyes her.”

Named Horse of the Year for 2009, the Eastern-based daughter of Medaglia d’Oro won 13 of 19 career starts, with five runner-up finishes, and earned $3.5 million

“I believe it will be hard to match,” Banke said about the Stonestreet filly’s 3-year-old campaign. “Going into the Triple Crown, going into races against boys in the Haskell and older males in the Woodward. Who does that? It was a campaign for the ages.”

Yet for all of the parallel roads they traveled, their paths never crossed. It was a glitch that did little to quell the wild passions of fan bases that were as devoted as the ones for the New York Yankees and Boston Red Sox - and would feud just as passionately as those who root for the two Major League Baseball arch-rivals.

Though Twitter was in its infancy, the internet had become the rage back then and it produced a rivalry unlike anything horse racing had ever seen before. With each 2009 victory by one of the horses, more fans jumped on the bandwagon and the divide between the two camps grew wider.

Their battleground became message boards or even the comments area for stories on one or both of the horses, and at times the bickering became quite heated and ugly.

“With most of my columns, if I got over a 100 comments, that was a lot,” said Steve Haskin, longtime Senior Correspondent for Blood-Horse magazine and Bloodhorse.com. “But with Zenyatta and ‘Rachel,’ if I got 350 that was a little. I can remember stories with 700 comments or more, and it got pretty nasty sometimes. We’ve never seen anything like it in horse racing. If you said something good about ‘Rachel,’ the Zenyatta fans would get all over you; and if you praised Zenyatta, the ‘Rachel’ fans blasted you. It was amazing. People were so opinionated. You got vilified by people on the opposite side, which was unusual for racing.

“Social media substitutes for fan clubs and people get closer to the horses through it. Had Twitter been popular then, I would have been reluctant to Tweet about either of them. You wouldn’t know what’s going to come out of the woodwork. You could say something positive, but people were so emotionally charged that some might perceive it as a negative comment and you’ll have 100 people jumping down your throat. During the Horse of the Year voting in 2009, if you came out and made a point on behalf of one of them, you were the devil to the other side.”

While the connections of both horses say they were spared the wrath of opposing fans in public, they were stunned at times by the tone of the internet bantering.

Rachel Alexandra (Eclipse Sportswire)

“I’ve never seen a response like that from fans,” Banke said. “Some of it was great and some it, well, was a little mean on both sides. There were definitely a lot of people interested in the two fillies, wondering who was better, what would happen if they met, and all of that. ... It was really something.

“I’ve met a lot of ‘Rachel’ fans over the years. I’ve even seen ‘Rachel’ tattoos. Never met anyone with a Zenyatta tattoo, but I’m sure there’s one out there.”

Why was there such fervent interest in the two horses? A fascination with a relatively new form of media played a role. So did the East vs. West divide. Yet beyond that, it was the quality and charisma of the champions that made them rock stars.

“In the long run, I believe Rachel Alexandra will be remembered for her amazing brilliance on the track and for being one of the most brilliant fillies of all-time. Zenyatta will be remembered for what she stood for off the track, even more than on the track,” Haskin said. “No horse in my lifetime affected people the way Zenyatta did. People told me how Zenyatta changed their lives. People with debilitating or terminal illnesses said all they wanted to do was see Zenyatta in person before they died. Some even claim it was Zenyatta that helped them recover. It was spiritual, like something from Billy Graham.”

The biggest dust-up came late in 2009 when Horse of the Year was indeed a two-horse race between Stonestreet’s fleet 3-year-old filly and the Mosses’ stretch-running 5-year-old mare, trained by John Shirreffs.

Both were undefeated in 2009 but Rachel Alexandra did not race after the Woodward on Sept. 5 as Jackson refused to run her in the Breeders’ Cup because it was contested on a synthetic surface at Santa Anita. In her absence, Zenyatta became the first – and only – filly or mare to beat males in the Breeders’ Cup Classic, the nation’s richest race.

Afterward, there was a movement among some Eclipse Award voters to allow split ballots so that a vote could be cast for both Distaff stars, but it failed to gain the needed momentum.

In the end, Rachel Alexandra carried all three voting blocs and defeated Zenyatta, 130-99, to become the first 3-year-old filly to earn Horse of the Year honors in the Eclipse era.

A year later, when Zenyatta suffered a loss to Blame in her final start, she was voted Horse of the Year.

“When we won the Breeders’ Cup Classic and weren’t voted Horse of the Year, I said ‘what do you have to do to get a little notice?’ ” Moss said. “Then we lost by four inches [in the BC Classic] but she was named Horse of the Year. To a certain extent we were happy it ended that way and I think the entire industry was happy it happened that way. She deserved it.”

Rachel Alexandra’s victory over Zenyatta at the ballot box only heightened the demand for the two horses to race and those fervent hopes seemed destined to be fulfilled when Oaklawn Park offered a $5 million purse if the two tangled in the Apple Blossom on April 9, 2010.

Both camps agreed to run in the race and hotels rooms in Hot Springs, Ark., were filled in a snap for that weekend.

But it never happened.

The rigors of her 3-year-old campaign caught up with Rachel Alexandra in 2010 and in her 4-year-old debut she suffered a stunning defeat at the hands of Zardana, a stablemate of Zenyatta, in the New Orleans Ladies Stakes at Fair Grounds. The following day, it was announced she would not run in the Apple Blossom.

“Rachel Alexandra wasn’t at her best in the New Orleans and Zardana beat her,” Smith said. “That was Zenyatta’s workmate. I used to give big head starts to her and blow by her on Zenyatta.”

Zenyatta after winning the Apple Blossom. (Eclipse Sportswire)

With the purse reduced to $500,000, Zenyatta ran in the Apple Blossom and prevailed by 4 ¼ lengths. As the year progressed, Zenyatta continued her winning ways until the Breeders’ Cup, while Rachel Alexandra struggled and was retired after squandering a 3 1/2-length lead at the eighth pole and finishing second in the Grade 1 Personal Ensign at Saratoga. She finished the year with two wins and three seconds in five starts.

“Rachel Alexandra was never the same at 4,” Haskin said. “Something happened to her over the winter. She just lost it. Steve Asmussen was putting all different kinds of bits on her because she was running with her head cocked. She had a few brief moments of glory at 4 but she got beat by fillies she never should have gotten beat by. But at 3, my goodness. The Woodward just gutted her and the two horses that made her run so hard, Macho Again and Bullsbay, were never the same after that, either.”

Rachel Alexandra’s retirement ended hopes that the two Queens of the racing world would meet in that year’s Breeders’ Cup at Churchill Downs. Yet, in hindsight, a race between two horses with diverse running probably would have done little to settle the issue of one’s superiority over the other.

“We saw what happened with Affirmed and Alydar,” Haskin said. “They had two contrasting running styles and Affirmed had a tactical advantage, which is why Affirmed won the vast majority of the races. If you’re going to have a rivalry between horses, it’s best that they have the same running style, but you rarely see that. A lot of rivalries were great while they lasted, but they didn’t prove who was the better horse. In a small field, if ‘Rachel’ got loose on the lead, I don’t know if Zenyatta could come from that far back and beat a filly like ‘Rachel.’ In the end, you look at their accomplishments, ‘Rachel’ with her total domination and fast times and huge margins and Zenyatta with her explosive, dramatic stretch runs.  You respect their place in history.”

For some of the connections, there are no regrets that fate did not allow the two superstars to square off.

“People will always talk about what would have happened if they raced, but we’ll never know the truth,” Smith said. “It was the greatest rivalry that never happened. Both sides have their opinion on who would have won. In some weird way, it would have been great to see them race, but I’m glad they didn’t. Why make one better than the other? They were each incredible for the game.”

And sometimes, there’s nothing wrong at all with having that lingering question which promises to keep the memory of two fabulous fillies fresh in the minds of the people who adored them.

“It’s better that they didn’t race for the legacy,” Banke said. “You always wonder ‘what if?’ and it keeps the mystery alive.”

The mystery and the rivalry, too.

The rivalry that never was.

Note: This story was originally published in August 2016 and has been updated.