LOUISVILLE, Ky. -- Rachel Alexandra looks ready to challenge the boys in the Preakness.
And after a day of jostling among owners of other Preakness hopefuls, it appears she'll get the chance.
Owner Jess Jackson declared the Kentucky Oaks winner primed for the second jewel of the Triple Crown following an easy four-furlong workout on Sunday at Churchill Downs.
Rachel Alexandra covered the half-mile in 48.40 seconds under exercise rider Dominic Terry, a work trainer Steve Asmussen called "beautiful."
It was all the evidence Jackson needed to send the 3-year-old filly, who he purchased last week for an undisclosed sum, to Pimlico for the 1 3/16th-mile race.
The process of getting the horse into a Triple Crown race, however, has grown complicated.
The Preakness is limited to 14 starters, with preference given to horses pre-nominated to the Triple Crown.
While Jackson is willing to pay the $100,000 supplemental fee required to make Rachel Alexandra eligible for the race, she could get bumped if 14 horses already nominated to the series are entered.
"Since it's Mother's Day, I wish I could announce to all mothers everywhere that this incredible filly is entered to take on the boys," Jackson said in a statement. "But Triple Crown rules may prevent us from sending her to Pimlico."
For a few hours Sunday, it appeared Rachel Alexandra would be all prepped with nowhere to run.
The probable Preakness field swelled to 15 late Sunday, including 14 pre-nominated horses and Rachel Alexandra.
One of the entries was Indy Express, a horse owned by Kentucky Derby winner Mark Allen. Allen told The Thoroughbred Times on Sunday he was entering the Indy Express solely to take away a starting spot from Rachel Alexandra.
Allen said his motives are professional, not personal.
Jockey Calvin Borel, who guided the 50-1 long shot gelding to a stunning 6 3/4-length win in the Run for the Roses, has already agreed to pilot Rachel Alexandra for the rest of the year. Borel went along for the ride as Rachel Alexandra won the Oaks by a record 20 1/4 lengths on May 1.
"I just want my rider back," Allen told the publication.
Mine That Bird trainer Bennie Woolley Jr. told The Associated Press late Sunday evening that Allen had changed his mind.
"He's rethought it and with the best interest of racing and the sport, he feels like it would be unfair to do that and she's going to run," Woolley said.
Allen wasn't the only one having second thoughts.
Hall of Fame trainer D. Wayne Lukas planned to enter a second colt, Luv Gov, in addition to Flying Private, who finished last in the Kentucky Derby.
Luv Gov is owned by Marylou Whitney, who also owned and bred Birdstone, sire of Mine That Bird. Whitney's husband John Hendrickson told several outlets on Sunday that Luv Gov will not stand in the way of Rachel Alexandra's bid to run in the Preakness.
Pioneerof the Nile, Musket Man and Papa Clem automatically make the Preakness field because they earned purse money in the Derby.
General Quarters, Friesan Fire and Big Drama are the next three in the field based on graded stakes earnings.
Terrain, Flying Private, Take the Points and Hull qualify next based on earnings in all non-restricted stakes races.
The final three spots are currently taken by Luv Gov, Tone It Down and Indy Express based on total career earnings. All 14 were pre-nominated to the Triple Crown before the Derby.
Rachel Alexandra would rank fifth on the list and bump all the others down one notch, if she had been pre-nominated.
Woolley has selected a backup rider for Mine That Bird if Rachel Alexandra runs, but plans on naming Borel the jockey during the Preakness draw on Wednesday.
"We've narrowed it down to a couple of guys but we're still waiting to see what happens with Calvin," Woolley said.
Pimlico oddsmaker Frank Carulli said he would make Rachel Alexandra the morning line favorite if she enters. Nellie Morse in 1924 was the last filly to win the Preakness.
Genuine Risk in 1980 and Winning Colors in 1988, who both came to Baltimore as Kentucky Derby winners, went off as the betting favorites in the Preakness but didn't win.
The most recent filly to go against the boys was Excellent Meeting in 1999. She finished last after being pulled up by jockey Kent Desormeaux.
Jackson, who owned 2007 Preakness winner Curlin, remains optimistic his stables' newest star will get a chance to run.
"I want the fans to know we are prepared to enter her and I am hopeful that her entry will be accepted," Jackson said. "I know we all want the thrill of seeing her race next weekend."
The last filly to enter a Triple Crown race was Eight Belles, who broke both of her front legs moments after finishing second to Big Brown in the 2008 Kentucky Derby.