ARCADIA, Calif. — The Breeders’ Cup Classic lost the Kentucky Derby and Preakness winner to injury, and it almost lost its other big draw — defending champion Curlin — to Santa Anita’s new synthetic surface.

The most radical change to the Breeders’ Cup in the last 25 years was tested Friday in five races exclusively for females that opened the two-day, season-ending championships.

Zenyatta stayed perfect, improving her career record to 9-0 with a 1½-length victory in the $2 million Ladies’ Classic in front of an announced crowd of 31,257. The races went off without incident on the synthetic surface.

“I thought it played extremely fair today,” said jockey Mike Smith, who won the Ladies’ Classic and Juvenile Fillies. “If you did the right thing on the lead, you could get away with it. You could be inside, you could be out. They’ve done a good job keeping the racetrack fair.”

Ventura won the $1 million Filly &Mare Sprint; Maram won the $1 million Juvenile Fillies Turf; Stardom Bound captured the $2 million Juvenile Fillies; and Forever Together took the $2 million Filly &Mare Turf.

Only after sending Curlin, the reigning Horse of the Year, to try the surface in workouts about a month ago did owner Jess Jackson and trainer Steve Asmussen decide to run him in Saturday’s $5 million Classic.

Jackson even made a special visit to personally inspect Santa Anita’s Pro-Ride surface that was installed in August. Races have been run on it for about a month, with five fatal breakdowns occurring, including four during morning workouts.

Curlin has made his reputation running on dirt, where he’s undefeated this year, and like several horses in this year’s event, has never competed on the mixture of sand, fibers and rubber.

“I think there’ll be a lot of evaluating going on with these races,” Hall of Fame trainer D. Wayne Lukas said. “I don’t know that it’s going to be all conclusive.”

The 14 Breeders’ Cup races — three are new this year — worth a record $25.5 million in purses are being run on a synthetic surface for the first time, leaving handicappers befuddled about how horses that run on American dirt and European turf will handle the new footing.

“It’ll be horrible,” Lukas said, referring to picking a winner. “You need to take seven horses in the superfecta and box them, just take your favorite number.”

Plenty of trainers, owners, and fans have questions about how the surface will affect the results. Those could carry into next year, too, when Santa Anita plays host again, marking the first time the event is held at the same track two years in a row.

Kentucky Derby and Preakness winner Big Brown won’t be here, having been retired because of a foot injury.

“I think the initial thrust of everybody thinking that it was going to be the track of the future is now backing up and saying, ‘Whoa, wait a minute, we better not just convert all these tracks overnight,”’ Lukas said.

However, the switch from dirt to synthetic helped attract a record 29 foreign horses, including many from Europe, where they train on similar surfaces.

“The synthetic surface is key this year because it’s expanded the number of races European horses would enter,” said Alastair Donald, director of the International Racing Bureau.

Count Jerry Moss, who owns Ladies’ Classic wagering favorite Zenyatta, among those with reservations about synthetics, a surface change mandated by the California Horse Racing Board for the state’s major tracks.

“Some of the synthetic tracks, they just stop the foot from going into the track at all so it’s a little jarring,” Moss said. “I don’t like that for racehorses. I prefer them to be able to get a little hold.”

Arguments have been made that synthetics are safer for horses and riders, and require less maintenance. Several prominent trainers, including Lukas and Hall of Famer Bobby Frankel, don’t buy them.

“We don’t have enough statistics,” Lukas said. “A lot of water has to go under the bridge before we can say without reservation that it’s a better surface injury-wise. Most injuries have happened on tracks that probably needed renovation from top-to-bottom anyhow.”

Rick Dutrow, who trains Big Brown, doesn’t see synthetic surfaces sweeping U.S. racetracks, especially at New York’s major tracks — Belmont, Aqueduct and Saratoga.

“Those tracks are safe enough,” he said, adding, “I don’t know anything about it and I’m not really interested in trying to find out.”

Bob Baffert’s Santa Anita-based stable has struggled in making the surface transition.

“I’m coping with it,” he said resignedly. “We all have to run on it.”

The racing industry has taken numerous hits this year on such issues as safety, steroids, and treatment of the horses.

“We’ve got our critics out there,” Lukas said, “and so perception that we are trying to do something is very important.”