DEL MAR, Calif. - More than four months have passed since Kelly Leak won the Sunland Park Derby, beating eventual Kentucky Derby winner Mine That Bird. It is time for a new milestone. Trading on that accomplishment is growing old.\nOn Sunday, Kelly Leak finally returns to racing in the $250,000 San Diego Handicap at Del Mar, his first start against older horses. In the Grade 2 San Diego, Kelly Leak will face a field that includes Well Armed, the winner of the $6 million Dubai World Cup in late March. Beating the Dubai World Cup winner would be a true feat.\nKelly Leak has been sidelined in recent months by minor illnesses. In May, Kelly Leak missed the Lone Star Derby because of a throat ulcer. In June, he missed the Affirmed Handicap at Hollywood Park because of a poor blood test.\n"I've had to stop and start a few times," trainer Mike Machowsky said.\nKelly Leak did not have a disruption in July, at least through Thursday, leading Machowsky to plan a comeback race in the San Diego.\nMachowsky is using the San Diego as a prep to the $1 million Pennsylvania Derby at Philadelphia Park on Sept. 7 or the $750,000 Super Derby at Louisiana Downs Sept. 19.\n"I want him ready in September," Machowsky said.\nKelly Leak is one of nine entered in the San Diego and will be ridden by Mike Smith. Machowsky says Kelly Leak is not in peak condition but good enough to challenge horses such as Well Armed; Mast Track, winner of the 2008 Hollywood Gold Cup; and Informed, who won the Californian at Hollywood Park in June.\n"He may be about 95 percent ready," Machowsky said. "Mike knows the horse."\nThe San Diego does not include Life Is Sweet, the 4-year-old multiple-stakes-winning filly.\nTrainer John Shirreffs said Thursday that Life Is Sweet had trouble adapting to Del Mar's Polytrack surface earlier this month and consequently missed a workout last weekend.\n"When she came down here, she was uncomfortable on the track for four days," Shirreffs said. "In the last two days, she's been better."\nOwned by Marty and Pam Wygod, Life Is Sweet was third in the Hollywood Gold Cup against males on July 11.\nWolf Tail staying with Cal-breds\nDespite Wolf Tail's unexpected win in Wednesday's $100,000 Graduation Stakes, trainer Doug O'Neill is planning a conservative approach for the rest of the Del Mar meeting.\nWolf Tail is likely to stay in the statebred division for the $100,000 I'm Smokin Stakes over six furlongs on Sept. 7.\nO'Neill was content that Wolf Tail won the Graduation, but admitted that the colt needs to accomplish more to be ready for a higher level of competition.\n"It wasn't the deepest race that we've seen," O'Neill said.\nRidden by Joel Rosario, who won three races Wednesday, Wolf Tail ($37.40) closed from seventh to win by a neck over 6-5 favorite Grace Upon Grace. Wolf Tail ran 5 1/2 furlongs in 1:05.15.\n"He showed a lot of heart down the lane," O'Neill said.\nGrace Upon Grace finished six lengths clear of third-place finisher Daylight Storm.\nWolf Tail is owned by breeder Ed Delaney. The colt was the first stakes winner for the stallion Strive, a 10-year-old by Deputy Minister. Wolf Tail was fifth once and second twice in his first three starts, all in maiden races at Hollywood Park. He has earned $79,320.\nRough week for Carava\nTrainer Jack Carava's stable was hit with its second fatal breakdown in three days on Thursday when Pocosin's Game Boy suffered a severe injury to his right hind leg after a workout. A 6-year-old gelding, Pocosin's Game Boy could not be saved. He had completed a half-mile workout in 49.80 seconds when pulled up.\nTuesday, the Carava-trained Maggie and Hope was euthanized after suffering a cannon bone injury during a workout. Earlier this week, the Carava-trained Mr Napper Tandy, the winner of the Grade 2 San Francisco Mile, underwent surgery for a fractured cannon bone and is out until the winter.\n"It makes you feel like you're doing something wrong," Carava said of the injuries. "There is no way to predict this kind of injuries. I feel terrible for the owner and the horse."\nCarava said the two fatal injuries have not changed the way he operates.\n"You can't start playing scared," he said. "You hope to get the bad luck out of the way."\nCarava said thoughts such as shipping the stable back to Santa Anita have crossed his mind, but that he has no plans to do so.\n"Shipping home doesn't make a lot of sense," he said. "I'd still have to ship down here to run. I'll watch everything closely and hope it gets better."