Rachel Alexandra is ready to run against the boys again, and that might mean a little more thoroughbred racing history is at hand.

"I expect the best is yet to come," co-owner Jess Jackson said this week in the buildup to Sunday's $1.25 million Haskell Invitational at Monmouth Park.

The best is yet to come? Wow.

New Jersey racing officials are hoping for a record crowd of more than 53,000 when the dazzling 3-year-old filly takes on Belmont Stakes winner Summer Bird and five other fellas in the 1 1/8-mile Haskell.

"It's going to be a very special day," predicted Carl Goldberg, chairman of the New Jersey Sports and Exposition Authority, which operates racing at Monmouth.

Every time Rachel Alexandra shows up, records come tumbling down.

After winning her first three starts this year to run her winning streak to four in a row, Rachel Alexandra overwhelmed fellow fillies by an astonishing 20 1/4 lengths in the Kentucky Oaks. The margin of victory was the largest since Churchill Downs began keeping records in 1910.

A few days later, Jackson and Harold McCormick purchased the filly and said it was time to take on the boys. She did, and promptly became the first filly in 85 years to win the Preakness Stakes, beating Kentucky Derby winner Mine That Bird by a diminishing length.

In late June, she was back with the fillies. Only two rivals dared to show for the Mother Goose at Belmont. Rachel, with regular rider Calvin Borel aboard, romped in stakes record time and by 19 1/4 lengths _ breaking Hall of Fame filly Ruffian's margin of 13 1/2 lengths set in 1975.

She will attempt to become the second filly to win the Haskell _ Serena's Song won it in 1995. It's also the first meeting of a Preakness and Belmont winner in the Haskell since 1987, when Belmont winner Bet Twice defeated Derby and Preakness winner Alysheba.

"Rachel's an incredible force in the industry," Jackson said. "Every time she runs, she sets a record by lengths, by beating the boys, by setting a record that Ruffian had. So I hope she runs up to expectations. She's in top shape. She's happy, she's prospering up at Saratoga."

On Sunday, it'll be showtime on the Jersey Shore _ the glamour girl's first appearance in Bruce Springsteen territory after wowing more than 100,000 racing fans in Louisville in the Oaks and 78,000 in Baltimore in the Preakness.

Rachel Alexandra is the 4-5 morning-line favorite in the field of seven 3-year-olds. Since the Mother Goose, Rachel has been training up at Saratoga under the watchful eye of Steve Asmussen, who took charge of the filly after the sale.

"She hasn't changed, that's the good thing," Asmussen said. "And Calvin knows her exceptionally well. All we're trying to do is keep her comfortable at all times."

The past two years it was Curlin who amazed Asmussen with his powerful stride and determination in becoming a two-time Horse of the Year. Now he has an even bigger star in Rachel Alexandra, who appears in the pages of this month's Vogue magazine, has several Web sites following her career and also is running to raise money for cancer research.

Jackson said there would be no embarrassment if his filly finished second in the Haskell, but winning would enhance her place in history.

"We've already proven we can run against colts, and I would hope that she would perform well in this race," Jackson said. "And if she should win, I think it just lengthens her legacy and claim to be one of the best of her generation."

Asmussen won't even say she's the best 3-year-old _ male or female.

"I'm glad I'm on her side," the trainer said. "I'm not judging anyone else's horse."

Let's not give Rachel the race before it's run, though.

Summer Bird is a formidable foe. He won the Belmont in just his fifth career start, and has filled out and matured in the eight weeks since defeating Dunkirk and Mine That Bird (with Borel aboard).

"We'll give her a run for the money," trainer Tim Ice promised.

Can he pull another upset?

"I'm not predicting anything," Ice said, "but Calvin Borel found that out in June."

Munnings, trained by two-time Haskell winner Todd Pletcher, comes into the race as one of the nation's top sprinters. Pletcher says stretching out to 1 1/8 miles is worth a chance.

The field may be the toughest yet for Rachel. Several other stakes winners are entered, including Arkansas Derby winner Papa Clem, Iowa Derby winner Duke of Mischief and Long Branch Stakes winner Atomic Rain. Bunker Hill rounds out the field.

"We're not looking for an easy race for her," Jackson said in explaining the decision to run in the Haskell. "We're trying to prove how good she is. And taking on another champion we haven't run against was attractive as well."

Jackson reiterated earlier this week that Rachel Alexandra would not run in the Breeders' Cup at Santa Anita in November because of the owner's dislike for synthetic racing surfaces. He plans to run Rachel next year, with the goal of the 2010 Breeders' Cup at Churchill Downs, where the main track is a traditional dirt surface.

As for Rachel's next race, just about everyone is hoping it's the Travers Stakes at Saratoga on Aug. 29 _ and a rare matchup of the three Triple Crown race winners.

The Travers already is on the calendar for the Birds _ Mine That Bird and Summer Bird.

Chip Woolley, who trains Mine That Bird, welcomes another shot at Rachel Alexandra.

"I think it's good for racing," Woolley said earlier in the week. "I think it's a big plus to have two great horses hooked up together. People would really turn out to watch and it's something that could really be hyped and play well for racing all across the country."

For now, Rachel Alexandra is playing well as a solo act.