03/30/2006 1:00AM

Barbaro still a mystery on dry track

Barbaro's only dirt race came on a sloppy track.

LOUISVILLE, Ky. - I wouldn't call Barbaro a vulnerable favorite in Saturday's Grade 1 Florida Derby, just likely to be heavily played. The public is fascinated by undefeated horses and tends to bet them as if they'll never lose, something that, of course, rarely happens.

This should create favorable odds on many of the other contenders, including my choice, Sunriver.

But first things first, and that entails an analysis of the horse to beat, who no doubt is Barbaro. In passing his first dirt test when he won the Holy Bull in the slop - after going 3 for 3 on turf - my feeling is that the public, believing that Barbaro has established himself as a true dirt horse, will bet him below his 8-5 morning-line odds.

Perhaps Barbaro is a legitimate dirt runner, but all the Holy Bull proved was that he could win in slop, and I've seen some turf horses over the years handle off tracks but not fast surfaces.

Different conditions are expected Saturday at Gulfstream, where the weather forecast calls for sun, sun, and more sun. Barring the unexpected, Barbaro and the 10 others expected to face him in the Florida Derby will race over a fast track.

It's anyone's guess how Barbaro will fare on a dry surface. He might love it, he might hate it.

There is no such uncertainty with Sunriver. Toss out his seventh-place finish in a sloppy renewal of the Holy Bull, and he has been first or second in all four of his starts on fast surfaces, albeit against maiden and first-level allowance company. Sunriver is also a two-time winner at the Florida Derby distance of 1 1/8 miles, having won an allowance at Gulfstream and a maiden race over Achilles of Troy at Aqueduct last November.

In the Gulfstream allowance, Sunriver rebounded from his poor Holy Bull effort to win a one-other-than on the Fountain of Youth undercard March 4, gamely turning back a stretch challenge from High Blues.

Admittedly, Sunriver didn't beat much - High Blues has just a single win from eight starts - but he did show more professionalism than he had in prior starts. Unlike in some of his previous races, when he had to be put into drives on the backstretch and turn to keep up, Sunriver was much more aggressive and willing, indicating to me that he is improving.

I also like that trainer Todd Pletcher and owners Aaron and Marie Jones are swinging for the fences by placing Sunriver in the Florida Derby. A full brother to champion Ashado by the late Saint Ballado, Sunriver seemingly has more to gain by winning this race than any other starter. A win likely provides him a second career as a high-priced sire.

Ungraded status hurts WinStar Derby

Thousands of miles away, in New Mexico, another Derby prep is being run Saturday at Sunland Park - that being the WinStar Derby. Take a glance at the field, and you'll wish you owned a 3-year-old, a horse trailer, and had the time to drive the horse to New Mexico.

Why is the field so soft for a $600,000 race? It isn't graded, and when more than 20 horses are entered in the Kentucky Derby, the field is limited to the 20 horses with the highest graded-stakes earnings. What happens, then, is that some horses being pointed to the Kentucky Derby are kept away from the WinStar Derby in favor of running in graded races. Indy Wildcat - who won the prep for the WinStar Derby, the Borderland Derby - is a good example. Lacking graded earnings, he is running in the Grade 1 Santa Anita Derby against Brother Derek rather than at Sunland Park.

Sunland Park is in a tough position. It is struggling to get top 3-year-olds because its big race isn't graded, and because it can't land these top horses, the graded stakes committee might not have the evidence it needs to assign the race graded status.

So who to play in the WinStar Derby? My choice is one that appears more likely headed to Woodbine for the Queen's Plate than to Churchill for the Kentucky Derby - Wanna Runner.

Bred in Ontario, Canada, Wanna Runner seems a perfect fit for the Queen's Plate, a race restricted to Canadian-bred 3-year-olds, and the WinStar Derby looks like a great launching pad to get him there. After running fifth behind Cause to Believe in the El Camino Real Derby at Bay Meadows, Wanna Runner may rebound to the quality form he displayed in finishing third to Brother Derek and Stevie Wonderboy in the San Rafael Stakes at Santa Anita.