DEL MAR, Calif. – Jockey Kyle Frey will miss the first half of August after spraining his knee when he was unseated during warmups prior to the eighth race at Del Mar last Friday, his agent, Bill Sadoo, said over the weekend. “He’ll be out of action for two to three weeks,” Sadoo said. “Until we get a couple of days away, we won’t have a clear idea. It’s so early in the process.” The incident occurred a few minutes before the start of a maiden claimer on dirt. Frey’s mount, Beat the Chalk, flipped and was withdrawn. Frey, the champion apprentice jockey of 2011, has won 20 races from 186 mounts this year. The 26-year-old Frey, who has won 656 races, won two Grade 3 stakes on Blended Citizen – the Jeff Ruby Steaks at Turfway Park in March and the Peter Pan Stakes at Belmont Park in May.