Trainer Beau Greely announced Tuesday that multiple grade I winner Borrego has been sidelined due to a small chip in his right front ankle. The 5-year-old son of El Prado is scheduled to undergo surgery Friday to remove the chip. He is expected to be back under tack 30 days after the operation, according to Greely, and will be pointed toward a defense of his 2005 title in the Pacific Classic (gr. I) in late August.Borrego, who is scheduled to be retired to stud at Wintergreen Farm in 2007, has won five of 20 starts, with eight placings, and earned $2,052,090. In addition to the Pacific Classic, the horse won last year's Jockey Club Gold Cup (gr. I).