That's according to California State Athletic Commission Executive Officer George Dodd, who today confirmed with MMAjunkie.com (www.mmajunkie.com) that the failed test was due to a banned performance-enhancer. Sonnen could not immediately be reached for comment. Sherdog.com first reported the failed test. According to the report, Dodd did not state which banned substance was detected in the failed screen. An official announcement is likely to come in the next few days. Sonnen is likely to face a long layoff either in the form of a suspension or if he plans to appeal the findings. On the heels of an epic trash-talking campaign that generated significant interest in their Aug. 7 bout at Oracle Arena in Oakland, Calif., Sonnen dominated Silva for more than four rounds in the UFC 117 pay-per-view headliner. However, with fewer this two minutes remaining in the fight, a grounded Silva secured a triangle choke and forced a tap-out for the shocking come-from-behind victory. UFC president Dana White promised an immediate rematch, and the title fight tentatively was planned for early 2011. However, with the failed drug test, a delay or new matchup for Silva likely will be in order. On the eve of the original meeting, Sonnen caused a bit of stir. During the UFC 117 weigh-ins, he squared off with Silva for the traditional pre-fight photo opportunity, and his back had many apparent lesions. Although messageboards were abuzz with speculation about potential steroid use, it was unclear what caused the marks, which were also partially visible at UFC 109  but essentially nonexistent at UFC 104. However, MMAjunkie.com medical consultant and columnist Dr. Johnny Benjamin cautioned that such skin problems could be caused by a variety of issues, and Sonnen passed drug tests at both UFC 104 and UFC 109. Despite the loss, Sonnen hadn't slowed his big-talking ways. During a recent UFC Fight Club Q&A session prior to UFC Fight Night 22, he said he'd make quick work of welterweight champ Georges St-Pierre, light-heavyweight title-holder Mauricio "Shogun" Rua and even heavyweight kingpin Brock Lesnar. But any matchups, including the Silva rematch, now appear on hold. I hope that we will see this rematch someday.