Trainer Jeff Mullins said Santa Anita Derby (gr. I) winner Buddy Gil will undergo arthroscopic surgery either Wednesday or Thursday to remove a small bone chip in the left front ankle of the Eastern Echo gelding who finished sixth in Saturday's Kentucky Derby.Mullins said X-rays of Buddy Gil's knees were taken initially on the morning after the Derby, and no chips were detected. However, he said, when Desperado Stables received an offer to buy the gelding, "We had a prepurchase exam done, and that showed the chip in his ankle." Dr. Larry Bramlage will perform the surgery. Mullins said Buddy Gil would return to California in about three weeks and could be back in training in as soon as five weeks.