LOUISVILLE, Ky. - Signaling her race-readiness, Rachel Alexandra worked a sharp six furlongs in 1:12 early Monday morning over a fast Churchill Downs racetrack.\nWorking under the temporary lighting system in place for three upcoming nighttime programs at Churchill, Rachel Alexandra went in splits of 12.40 seconds, 24.40, 36.40, 48.40, and 1:00 before galloping out seven furlongs around the clubhouse turn in a strong 1:24.80. Regular exercise rider Dominic Terry was aboard.\nTrainer Steve Asmussen watched the workout from the grandstand before returning to his barn to watch Rachel Alexandra cool out. Asmussen spoke only briefly and did not commit to a race for Rachel Alexandra, the star filly who defeated males in her last race, the May 16 Preakness. The Grade 1 Mother Goose, a 1 1/8-mile race restricted to 3-year-old fillies at Belmont Park on June 27, has been the subject of considerable speculation as a likely next start.\n"She's just adding to what she's already doing," said Asmussen. "She's doing good."\nRachel Alexandra was one of maybe a dozen horses on the racetrack at the time of her workout, which came shortly after 5:30 a.m. Eastern. The track normally opens for training at 6, but Churchill officials are testing the lights before daybreak Monday and Tuesday and have opened the track for training at 5. Rachel Alexandra is part of the second set of horses that Asmussen and assistant Scott Blasi take to the track each morning, and they saw no reason to change their routine.\nThere certainly was no mad rush to the track at 5, as the majority of trainers did not alter their schedules to have their horses out early. A 3-year-old filly named Country Living, trained by Bret Calhoun, was the first to step onto the track a few minutes after 5. There was only a modicum of activity until shortly before 6, when the pace picked up to its normal level.\nFor the first time in its 135-year history, Churchill will conduct night racing at the current spring meet. Programs starting at 6 p.m. will be run June 19, June 26, and July 2.\nMost of the temporary lights are stationed outside of the circumference of the one-mile oval and are pointed inward, except for on the backstretch, where lights are spaced at regular intervals to the inside of the turf course in the infield, from where they point outward. None of the lights are focused on the turf, which will not be used for racing after dusk on any of the three upcoming programs.\nBernie Flint was one of a handful of trainers who made it a point to have some of his horses out early Monday to test out the lighting system. "We went after it to find out what's going on," said Flint. "I thought it was important to have these horses get a look-see at it if they're going to run over it.\n"Everything seemed good. The horses seemed to handle it fine. One horse jumped one shadow one time, and she's capable of doing something like that anyway. From what I could tell, 99 percent of the horses handled it all without any problem. The whole set-up is okay."