Five white undercover cops slammed retired black tennis star James Blake to the ground outside his midtown hotel Wednesday in a violent case of mistaken identity.

The 35-year-old Blake, once ranked No. 4 in the world, suffered a cut to his left elbow and bruises to his left leg as the law enforcement quintet handcuffed and held him for 15 minutes outside the Grand Hyatt.

"It was definitely scary and definitely crazy," said Blake, adding that none of the men initially identified themselves as a police officer.

His right eye appeared a bit red hours later at the hotel. The cops were investigating a credit card fraud operation when they took Blake to the ground around noon. The Harvard-educated Blake was only turned loose when a former cop recognized the man in cuffs and alerted the arresting officers, a police source said. "That is James Blake, the tennis player," the retiree told them. The first cop involved never apologized to Blake for the physical thumping or the brief arrest, the ex-player recounted.