By Rick Reeno has confirmed that WBO middleweight champion Dmitry Pirog (20-0, 15KOs) suffered a back injury in training, which in turn has forced him to withdraw from a highly anticipated unification with IBO/WBA "regular" champion Gennady Golovkin (23-0 20KOs). The fight was scheduled to take place on August 25th with HBO televising.

According to promoter Artie Pelullo, Pirog injured his back while hitting a tire with a sledgehammer - a popular exercise among fighters. Pirog will be out 90 to 120 days.

The HBO card will go forward with Golovkin in the main event, according to Pelullo.