She's a mare set to race against a dozen of the world's most daunting male horses for the first time in her career, but Zenyatta seems to be the one inspiring fear.

The 13-0 Zenyatta was entered in Saturday's $5 million Breeders' Cup Classic at Santa Anita on Tuesday instead of the Ladies' Classic she won last year, giving a boost to the big race's profile and throwing a bit of a scare into some of the boys.

"We have to be next to Zenyatta in the gate, so hopefully she don't intimidate us too much, as big as she is," joked Tim Ice, trainer of Belmont and Travers stakes winner Summer Bird, who drew the No. 3 post just inside the 5-2 morning line favorite.

Trainer Bob Baffert's Pacific Classic winner Richard's Kid will be a few stalls outside of the mighty mare, but the white-haired Hall-of-Famer has got the same feeling.

"I hate to run against her, I didn't want to see her in there," Baffert said.

But Baffert insisted he wasn't entirely unhappy to see Zenyatta among the Classic starters.

"If we're gonna get beat, I don't mind getting beat by Zenyatta," said Baffert, who will saddle favorites in the Breeders' Cup Juvenile and Sprint. "She's a great mare, we're big fans of hers. And if I do beat her I hope she runs second. For racing, that'll make for a great championship day."

The 5-year-old Zenyatta will break from the No. 4 post with Mike Smith in the saddle in the 1 1/4-mile Classic. Owners Jerry and Ann Moss and trainer John Shirreffs kept everyone guessing until the last minute by also pre-entering Zenyatta in Friday's Ladies' Classic.

"We think she deserved a shot," Jerry Moss said. "She's done everything right, and she deserves to be here."

Only three other females have tried the Classic. Triptych was sixth in 1986, Jolypha finished third in 1992 and Azeri was fourth in 2004.

Zenyatta's considerable competition includes Irish import Rip Van Winkle, the 7-2 second choice, and 9-2 third choice Summer Bird. Richard's Kid and Kentucky Derby winner Mine That Bird are among six horses at 12-1.

Both Summer Bird and Mine that Bird have already finished a disappointing second to a female this year when each was trumped by the filly Rachel Alexandra _ Summer Bird in the Haskell Invitational and Mine That Bird in the Preakness Stakes.

Despite a stellar year that some say surpasses Zenyatta's, Rachel Alexandra did not make the trip to the Breeders' Cup. Her owner Jess Jackson doesn't like Santa Anita's synthetic surface.

Zenyatta is very much at home on the surface, where she's earned 11 of her 13 wins, including three on Santa Anita's Pro-Ride.

Her two highest rated challengers _ Rip Van Winkle and Summer Bird _ will be racing on the surface for the first time.

Ice dismissed questions about Summer Bird handling the surface. Trainer John Sadler told the Daily Racing Form Summer Bird didn't handle it well when she was an unraced 2-year-old in his barn.

"He's had no issues at all," Ice said of Summer Bird. "He adapts well wherever I take him."

Ice said the colt leaving Sadler's barn "had nothing to do with the surface."

Mine That Bird, upset winner of the Kentucky Derby, finished sixth in the Oct. 10 Goodwood Stakes at Santa Anita, but trainer Chip Woolley insists "he's a lot more on his game," after training for several weeks at the track.

"He's beat the best around at least once or twice," Woolley said.

Zenyatta could have faced a further challenge from Rip Van Winkle's stablemate Mastercraftsman, but trainer Aidan O'Brien entered him instead in the Breeders' Cup Dirt Mile, where he was made the 6-5 favorite.

Fourteen races worth 25.5 million will be run Friday and Saturday at Santa Anita. A total of 149 horses were entered.

Without Zenyatta, the Ladies' Classic attracted a field of eight, led by early 9-5 favorite Music Note.

Baffert will try to repeat in the $2 million Juvenile, where his colt Lookin at Lucky was installed as the 8-5 early favorite. Baffert also has the 7-5 morning line favorite in the $2 million Sprint with Zensational, who drew the No. 1 post. Baffert is going for his third consecutive win in the six-furlong race.

Conduit is the 7-5 morning line favorite in the Turf, and fellow Ireland-bred Goldikova will defend his title as the early 8-5 favorite in the Turf Mile.

Ventura is the defending champion and 8-5 early favorite in the Filly & Mare Sprint.