SANTA ANA, Calif.—Michael Avenatti, the brash lawyer recently sentenced to 2 1/2 years in prison a $25 million extortion case in New York, is expected to face a trial Wednesday in California on charges he embezzled millions from his clients. Opening statements are scheduled in Santa Ana in the second trial this month for Avenatti. He is expected to represent himself in the case after U.S. District Court Judge James V. Selna on Tuesday granted his request to do so. Federal prosecutors in Southern California have accused the 50-year-old lawyer, who is currently suspended from practicing law in California, of cheating five of his clients out of nearly $10 million by negotiating and collecting settlement payments on their behalf and funneling them to accounts he controlled. In one case, authorities said Avenatti collected $4 million from Los Angeles County for a man who suffered injuries in custody and was left …