What do you do with a champion filly who won her title for her performances on turf at age 2? Why, you run her on dirt, too, of course, and in the Longines Breeders’ Cup Distaff, the World Championships’ signature contest for fillies and mares, no less.

Len and Jon Green’s D. J. Stable has campaigned its share of high-level horses — Wonder Wheel, Jaywalk, and Webslinger to name a few — but their daughter of Medaglia d’Oro out of the Uncle Mo mare Tiffany Case has made a name for herself with graded stakes wins on both dirt and turf. Her versatility puts her in the same company as John Henry, Animal Kingdom, and Wise Dan and champions who excelled on both surfaces.

Nitrogen exercises at Del Mar (Anne M. Eberhardt/BloodHorse)

For trainer Hall of Fame trainer Mark Casse, the 2024 Canadian champion 2-year-old filly reminds him of a racehorse near and dear to his heart, War of Will. In addition to winning the 2019 Preakness Stakes, giving Casse his first American classic, the son of War Front also turned in a stellar performance on the Keeneland green in the 2020 Maker’s Mark Mile. When asked if Nitrogen is as talented as the strapping classic winner, the trainer replied, “maybe more.”

“Number-wise, whether it’s Beyer [Speed Figures] or Thoro-Graph, her dirt numbers are superior,” Casse said. “Of course, she’s matured as well and gotten older. As they get older, their numbers tend to improve. I think if we ran her back on grass, her numbers would probably improve as well. But right now, if you look at Thoro-Graph number, her best Thoro-Graph number ever on the grass was seven, and her best dirt race is a one. Humongous difference.” 

Casse and the Greens might not have discovered that Nitrogen — so named because Casse said “this filly breathes different air” — was a multi-surface marvel were it not for the off-the-turf Wonder Again Stakes at Saratoga Race Course in July. Originally scheduled to be run as a Grade 2 at 1 1/8 miles on the turf, inclement weather necessitated a move to the dirt. That was when the trainer had to decide whether to keep her in the race or scratch her.

“The D. J.  people said, ‘Look, we’ll take the responsibility if she loses.’ That made my decision much easier,” Casse said.

Reduced to a mile, a field of three, and a Grade 3 race, the Wonder Again turned in a blockbuster performance for Nitrogen, who bested second-place finisher Bessie Abott by 17 lengths.

“I was amazed. She ran one-fifth [of a second] slower than they ran the Met Mile that day,” Casse said. “When I saw that and with the ease that she did it, I knew that she could do it.”

In her next start, the Belmont Oaks Invitational Stakes, a 1 1/8-mile Grade 1 on the turf, Nitrogen had a head advantage at the top of the stretch and dueled with Fionn to the finish line, the latter eking out a nose victory.

Casse was all smiles the day after the Alabama win. (BloodHorse/Skip Dickstein)

Casse then switched her back to dirt for the Grade 1 Alabama Stakes presented by Keeneland Sales, in which she then faced Longines Kentucky Oaks winner Good Cheer and Grade 1 winner La Cara, and Nitrogen proved up to the task in a 1 ½-length victory. With grades stakes wins on both dirt and turf, Nitrogen entered rare air, a dual surface threat who is getting better with age.

Nitrogen enters the 1 1/8-mile $2 million Breeders’ Cup Distaff as the second choice on the morning line behind Bob Baffert’s 4-year-old filly Seismic Beauty, winner of the Clement L. Hirsch Stakes Presented by Oak Tree Racing Association Aug. 2 at Del Mar. Casse’s filly comes into the race with experience at the seaside California racetrack, but not on the dirt: her third in last year’s Breeders’ Cup came in the John Deere Juvenile Fillies Turf. Yet Casse remains quietly confident about his star’s chances on Saturday, four weeks after her second by a head to fellow Distaff starter Gin Gin in the Grade 1 Juddmonte Spinster Stakes at Keeneland.

“She likes to run about every four to five weeks,” the trainer said. “That’s why we chose the Spinster.”

Primed for another winning turn on the dirt, a Distaff win would very likely seal her claim for leadership of the 3-year-old filly division and show once again why this daughter of Medaglia d’Oro earned the name Nitrogen.