Kent Desormeaux, the nation's leading jockey, separated his left clavicle in a first-race spill at Laurel yesterday and could be sidelined up to six weeks.

Beltline, who finished first in the race under jockey John Baboolal, was disqualified and placed last for precipitating the accident.

Desormeaux was hurt when his mount, Marcia's Moon, fell on the backstretch after clipping the heels of Light Performer shortly into the 6 1/2-furlong race. Light Performer, ridden by Russell Reynolds, had been outside of Marcia's Moon, but when Baboolal angled Beltline inside from post position 8, he appeared to force Light Performer into Desormeaux's path.

"{Baboolal's} horse came over a little bit, and I had to protect my horse by moving {left}," Reynolds said. "I could feel my horse get his heels clipped, but I didn't know who it was behind me."

Wish It Was, who was trailing the field under jockey Jimmy Edwards, then hurdled Marcia's Moon, narrowly missing the filly's head.

"I was just trying to pick out a spot to land," said Edwards. "I thought I might be going down myself."

Laurel's racing stewards immediately called for an inquiry. After reviewing films, they disqualified Beltline (10 to 1) and promoted Let 'em Fly from second to first. Let 'em Fly paid $49.40 to win.

Baboolal maintained his innocence. "I don't think I bothered anybody," he said. "I don't feel like I pushed that horse into {Desormeaux's} path. I thought I was by them."

After the fall, Desormeaux lay on his stomach beneath the rail, then walked around briefly before a track ambulance transported him to Laurel's first-aid station. He then was taken to Greater Laurel-Beltsville Hospital for X-rays, which confirmed the separation.

According to Benjamin Manchester, Laurel's supervising physician, Desormeaux may be sidelined only one to two weeks if the collarbone is wired in place. Otherwise, Manchester said, Desormeaux probably will be out four to six weeks.

For Desormeaux, the mishap was exceptionally ill-timed. The nation's leading jockey of 1987 had ridden at least one winner every racing day since Jan. 5 and had 20 victories over the previous six days for a total of 89 this year. He began yesterday's card on pace to win 592 races; Chris McCarron set the world record of 546 victories in 1974 (although he didn't begin until February that year).

The injury also will deny Desormeaux increased visibility and potentially lucrative riding assignments in the upcoming days. He was scheduled to ride Thirty Eight Go Go, the champion Maryland-bred juvenile filly of 1987, in Wednesday's Bonnie Miss Stakes at Gulfstream Park, and unbeaten Triple Crown nominee Finder's Choice in the Hirsch Jacob Stakes, next Friday's opening-day feature at Pimlico. He also stands to miss the mount astride the undefeated stablemate of Finder's Choice -- Private Terms -- in the Federico Tesio Stakes at Pimlico March 12.

Moreover, four horses Desormeaux had been scheduled to ride yesterday were victorious.

"I feel bad for Kent, and I hope he's okay, but he rides too close {to other horses}," said the veteran Edwards. "I hope he learns from this."