IBF, WBO and WBA light heavyweight champion Sergey Kovalev (28-0-1 25KOs) knocked out Nadjib Mohameddi (37-4 23KOs) in the third round in the Main Event of HBO Boxing telecast from Mandalay Bay Events Center in Las Vegas, NV. Kovalev outclassed the relatively obscure to American airwaves, Mohameddi, who was out