While it first appeared that trainer Michael Matz's potential return to the Kentucky Derby got one step closer yesterday when Lexington Stakes winner Slew's Tizzy's trainer said they were leaning toward not running in the May 5 Derby, another glitch may have developed.

The Derby field will be limited to the top 20 entrants based on graded earnings, and the Matz-trained Chelokee, with $100,000, was tied for 22d on a list of expected Derby entrants. But according to a report on bloodhorse.com, California Derby winner Bwana Bull arrived at Churchill Downs on Tuesday and will run in either Saturday's Derby Trial Stakes or the Derby.

Bwana Bull has $125,000 in graded earnings, and his unexpected entry would knock Chelokee back to a tie for 23d with Reporting for Duty. A firm decision on Slew's Tizzy, who is 13th on the list with $205,000, is expected tomorrow.

Tesio winner Xchanger, who is 15th with $209,890, may go straight to the Preakness but no decision has been made.

If Bwana Bull is in the Derby picture, then Teuflesberg would move into the field only if both Slew's Tizzy and Xchanger defect. That would leave Imawildandcrazyguy, with $104,000, ahead of Chelokee.

And even then, Chelokee would need a tiebreaker draw of lots to get into the race, which Matz won last year with Barbaro.