CHICAGO - Sportsman's Park has endured a rough ride through its last few seasons as it converted to a dual-purpose auto and horse racing facility, struggling to convince fans, horsemen, and the Illinois Racing Board that the track could provide a viable Thoroughbred racing venue. Sailing has been only slightly smoother this year, with the track forced to deal with the revamping of its most important race, the $500,000 Illinois Derby, which is to be held Saturday.

That's a major switch from previous seasons, when the Illinois Derby was held a week after the Kentucky Derby. Sportsman's was forced to alter the schedule this year, thanks to an upheaval in Chicago racing dates awarded by the Illinois Racing Board. The Sportsman's meet will be over this year when the traditional Illinois Derby date rolls around.

"We didn't have a whole lot of choice in the matter," said Allan Plever, racing secretary at Sportsman's the last two years. "We had to choose a new date. We discussed this pretty thoroughly last fall, and decided April 7 was our best day."

Now the Illinois Derby is a Kentucky Derby prep run four weeks before the Derby itself. There are two other such races Saturday, the Grade 1 Santa Anita Derby and the $500,000 Lone Star Derby. The three races are to be linked in a national pick three wager.

All things considered, the Illinois Derby will fare pretty well, as a solid group of 10 3-year-olds were entered Tuesday in the 1 1/8-mile race. The field is headed by Dream Run, a troubled and promising fourth in the Grade 1 Florida Derby in his last start; Percy Hope, winner of the Rushaway Stakes on the Spiral Stakes undercard at Turfway Park; and Distilled, an impressive Gulfstream Park allowance winner in his last race.

Trainer Tony Reinstedler entered both Percy Hope and Weston Field, but said Tuesday that Percy Hope might end up racing in the Lone Star Derby.

"Sportsman's was the original plan," Reinstedler said. "But there were some defections at Lone Star" that influenced Reinstedler's thinking. There is a plane from Kentucky, where Percy Hope is training, to Dallas this week, and Reinstedler said it was possible Percy Hope would be on it.

None of the obvious contenders has yet arrived in Chicago, with most scheduled to ship here Thursday or Friday. Dream Run currently is training with Paul McGee at Churchill Downs, while Distilled flew from south Florida to Keeneland on Tuesday morning. Trainer Todd Pletcher said Distilled, who worked five furlongs Monday in 1:02, would van from Keeneland to Sportsman's on Friday.

The speedy Distilled, who will be ridden by Mike Smith, drew post 3, a position Pletcher said was very favorable. Dream Run, to be ridden by Sportsman's leading rider, Randy Meier, drew post 5, and Percy Hope will break from post 9.