Ren-Mar Thoroughbreds' homebred Sky Jack, last year's winner of the Hollywood Gold Cup (gr. I), is back in serious training at Hollywood Park for trainer Doug O'Neill and could return to action as soon as the end of the current Hollywood meeting. A 7-year-old California-bred son of Jaklin Klugman, Sky Jack underwent surgery to remove a bone chip from his right knee in September, an injury he likely suffered during his 11th place finish in last summer's Pacific Classic (gr. I) at Del Mar. On Monday, Sky Jack worked five furlongs in 1:02 4/5 handily over his home track of Hollywood Park. It was the gelding's third work since his surgery. "He's about three or four works away from being ready," O'Neill said. "I hate to use the old cliché, but he'll tell us when he's ready to run." Sky Jack isn't a stranger to layoffs. He was on the sidelines for more than nine months from 1999 to 2000 and shelved again for 15 months after winning the 2000 Native Diver Handicap (gr. III). He returned in good enough shape last year to win the Mervyn LeRoy Handicap (gr. II) and Hollywood Gold Cup. Overall Sky Jack has earned $929,267 from a career line of 15-8-2-2. O'Neill feels it will be particularly to find a new rider for Sky Jack due to the recent retirement of Hall of Famer Laffit Pincay Jr. Together Sky Jack and Pincay teamed up for six of the gray's eight wins. "They did make a great team," O'Neill said. "I don't know about (which rider he'll use.) I'll have to talk to the owners about that." O'Neill also said that top sprinter Avanzado, the runner-up in the March 29 Dubai Golden Shaheen (gr. I) at Nad Al Sheba Racecourse, has also returned to serious training after a brief freshening. The Argentine-bred son of Luhuk posted his first work since the World Cup on Saturday at Hollywood, earning a time of 1:02 for five furlongs. "Hopefully he'll be ready to run by the Triple Bend," O'Neill said. The Triple Bend Breeders' Cup Handicap (gr. I) is a six-furlong main track test set for July 5 at Hollywood Park. Avanzado, who won a graded stakes in his homeland and placed in five others, was imported to North America in mid-2002 and immediately went on a three-race win streak, picking up scores in an optional claiming race, the Pirate's Bounty Handicap and the Forest Hills Handicap (gr. II). After a rough break in the El Conejo Handicap (gr. II) produced a sixth-place on New Year's Day, Avanzado won the Palos Verdes Handicap (gr. II) by 4 ½ lengths, earning a trip to Dubai. Avanzado has a career bankroll of $773,543 from a record of 22-9-4-2.