Rocky IV

Ivan Drago, a Russian Soviet boxer, arrives in the United States with his wife, Ludmilla, and a team of trainers from the USSR and Cuba. His manager, Nicolai Koloff, takes every opportunity to promote Drago's athleticism as a hallmark of Soviet superiority. Motivated by patriotism and an innate desire to prove himself, Apollo Creed challenges Drago to an exhibition bout. Rocky has reservations, but agrees to train Apollo despite his misgivings about the match. He asks Apollo whether the fight is against the Soviet, or "you against you?"
During a press conference regarding the match, hostility sparks between Apollo and Drago's respective camps. The boxing exhibition takes place at the MGM Grand Hotel in Las Vegas. Apollo enters the ring in an over-the-top patriotic entrance with James Brown performing "Living in America" complete with showgirls. The bout starts tamely with Apollo landing several punches that have no effect on Drago. It soon turns serious though, as Drago starts to retaliate with devastating effect. By the end of the first round, Rocky and Apollo's trainer, Duke, plead with him to give up, but Apollo refuses to do so, and tells Rocky not to stop the match. Drago continues to pummel him in the second round, and despite Duke begging Rocky to throw in the towel, he reluctantly honors Apollo's wish. Eventually, Drago lands one final punch that knocks Apollo to the ground, killing him. In the immediate aftermath, Drago displays no sense of remorse commenting to the assembled media: "If he dies, he dies."
Enraged by Drago's cold indifference and feeling a deep sense of guilt, Rocky decides to avenge Apollo's death by fighting Drago himself. Drago's camp agrees to the fight but the conditions are that it must be in the Soviet Union on Christmas Day in an unsanctioned 15-round bout to protect Drago from the threats of violence he has been receiving in America. Rocky travels to the USSR without Adrian, setting up his training base in Krasnogourbinsk with only Duke and brother-in-law Paulie to accompany him. To prepare for the match, Drago uses very high-tech equipment, steroid enhancement, and a team of trainers and doctors monitoring his every movement. Rocky, on the other hand, throws heavy logs, chops down trees, pulls an overloaded snow sleigh, jogs in heavy snow with treacherous icy conditions, and climbs a mountain. Adrian arrives unexpectedly to give Rocky her support after initially refusing to travel to the Soviet Union because of her doubts on his fighting chances. Her presence increases Rocky's focus and enhances his training.
Drago is introduced with an elaborate, patriotic ceremony that puts the home crowd squarely on Drago's side and against Rocky. In contrast to his match with Apollo, Drago immediately goes on the offensive and Rocky takes a fierce pounding. Drago even throws Rocky around the ring with impunity. Rocky comes back toward the end of the second round; a right hook inflicts a cut below Drago's left eye that silences the crowd and prompts Rocky to continue punching Drago even after the bell rings. While Duke and Paulie cheer Rocky for his heroism, they remind him that Drago is not actually a machine, but a normal man. Ironically, Drago comments that Rocky "is not human, he is like a piece of iron" with his own corner reprimanding him for being "weak" in comparison to the "small American."
The two boxers continue their battle over the next dozen rounds, with Rocky holding his ground despite Drago's powerful punches. His resilience rallies the previously hostile Soviet crowd to his side, which unsettles Drago to the point that he shoves Koloff off the ring for berating his performance. Rocky finally takes down Drago in the last round, winning by knockout to the shock of the Soviet politburo members watching the match. A bloody and battered Rocky gives a victory speech, acknowledging how the local crowd's disdain of him turned to respect. He compares it to the animosity between Soviets and Americans, and says that seeing him and Drago fight was "better than 20 million," implying war between their two countries. Rocky finally declares, "If I can change, and you can change, then everybody can change!" The Soviet General Secretary stands and passionately applauds Rocky, and his aides follow suit. Rocky ends his speech by wishing his son a Merry Christmas, and raises his arms into the air in victory as the crowd applauds on Christmas Day.

Question: When did Rocky knockout Drago?
Answer: The last round of the 15-round bout.