The frontiers that are left for Rachel Alexandra to conquer are already getting scarce 12 races into her career.
Her own gender has barely been able to get within 20 lengths of her since April. When dropped in against some of the best 3-year-old colts — in the middle of the Triple Crown no less — she came away with another piece of immortality.
Hard as it may be to find a challenge for the filly, Sunday's Grade I, $1,250,000 Haskell Invitational at Monmouth Park appears to have come up with a pretty tall order for the Preakness Stakes winner.
Not only will Rachel Alexandra attempt to defeat a top class of males again, she will try to vanquish yet another classic winner. Belmont Stakes winner Summer Bird is among six other entered in the 11⁄8-mile race.
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"We're not looking for an easy race for her. We're trying to prove how good she is," owner Jess Jackson said during a teleconference this week. "And taking on another champion we haven't run against was attractive as well."
Given the nature of Rachel Alexandra's most recent start, staring down the boys again seemed to be the only option available for a significant test.
In her first start following a 1-length win over Kentucky Derby winner Mine That Bird in the Preakness, Rachel Alexandra won the Grade I Mother Goose Stakes by a dazzling 191/4 lengths and set a stakes record despite being geared down by jockey Calvin Borel in the stretch.
Jackson admitted the incentive to come to the Haskell was heightened when the track raised its $1 million purse by another $250,000.
"Well, of course money is a reward for having taken the risk, and I advocated that it would be nice if they did increase the purse," Jackson said.
Landing Rachel Alexandra was an undeniable coup for Monmouth Park, but the bay filly is not the only star in the field.
The lightly raced Summer Bird won the Belmont by 23/4 lengths in just his fifth career start, displaying a great turn of foot in the stretch despite having to come wide.
"It's definitely surprised me," trainer Tim Ice said of the colt's development. "He showed us a lot of ability early, but for him to make so much progress in such a short time was a surprise.
"I'm not making any predictions, but I think we'll give Rachel Alexandra a run for her money."
Multiple graded stakes winner Munnings is coming off a 21/4-length win against older horses in the Grade II Tom Fool Handicap at Belmont on July 5, but he has yet to win beyond 7 furlongs.
Although Munnings has the capability to challenge Rachel Alexandra on the front end, the filly has demonstrated on more than one occasion — including the Mother Goose — she is just as effective laying off the leaders as she is setting the fractions.
"I won't say she'll be on the lead, but she'll be awfully close," Borel said. "I mean if she breaks good and puts me in a spot, we'll be perfect."