LEXINGTON, Ky. — The fear here is we have seen the last of Justify on the nation’s racetracks, what with Tuesday’s news that the Triple Crown winner has been taken out of training to deal with a possible ankle injury.

That is an unfortunate development not just for the horse, his health being top priority, but also for racing fans who not only want to see him race again, but also to find the answer to an important historical question.

Just how good is Justify?

By all means, he was plenty good enough to become just the sport’s second Triple Crown winner in 40 years, joining a select group of just a dozen thoroughbreds. He did that in shooting-star fashion, winning six races in 112 days, the first Kentucky Derby winner to not race at age 2 since Apollo in 1882, the first undefeated Triple Crown winner since Seattle Slew in 1977.

According to his ownership group, and specifically WinStar Farm in Woodford County, the intention was/is for Justify to continue competition through the rest of the calendar year. That plan has been placed on hold, however, with the news that the son of Scat Daddy had twice developed filling, or swelling, in an ankle.

“Justify had some filling in his left front ankle a week ago, which subsided in a couple days,” trainer Bob Baffert said in a news release Tuesday afternoon. “I trained him last week and the filling came back. We want to get him checked out.”

Unfortunately, if Justify does not make it back to the track, his career, when sized up against the all-time greats, will end up with a legacy mark of incomplete.

For one thing, an important thing, Justify will not have beaten an older horse. All six of his races were run against 3-year-olds, starting with his Feb. 18 debut, through an allowance win and his four graded stakes victories — the Santa Anita Derby, the Kentucky Derby, the Preakness and the Belmont.

Thus Justify would suffer in comparison to American Pharoah, who in 2015 became the first thoroughbred to win the Triple Crown in 37 years.

After a brief rest, Pharoah ran away with the Sept. 2 Haskell Invitational before a raucous crowd of 60,983 at Monmouth Park on the New Jersey shore. Alas, in what Baffert has called one of his biggest regrets, Pharoah was shipped back to California, then to Saratoga in upstate New York, where he was beaten by three-quarters of a length by Keen Ice in the Travers on Aug. 29.

Then, in a dramatic act of redemption, Pharoah rebounded to dominate the Breeders’ Cup Classic at Keeneland. He rolled by 6 1/2 lengths on Oct. 31, 2015, becoming the first horse to accomplish the so-called Grand Slam — the Triple Crown and the BC Classic. FYI: Four of the seven horses American Pharoah beat that day were 4-year-olds.

The hope was that we would see Justify duplicate that Grand Slam feat, or at least try. Baffert had already mentioned a personal preference toward a start in the Haskell, a Grade 1 race he has won eight times. That is now out.

Even if Justify can return to training — he has not had an official workout since before the June 9 Belmont — he would not be ready in time for the trip to the swamps of Jersey. His first probable post-Triple Crown start would be the Travers, scheduled for Aug. 25.

Another big loser in all this would be Churchill Downs, which will play host to the Breeders’ Cup Nov. 2-3 in Louisville. Surely the good folks between the twin spires had their fingers crossed in hopes of a return trip by Justify, who after the Derby did the bulk of his Preakness and Belmont training at the Downs.

Maybe, as many hope, that will still be the case. The guess here is that Justify’s racing days are over, but we would be happy to be wrong. Like all of racing, we would love to see where he ranks with the all-time greats.