Blast Off! Superman and Steel notice that the engines of Engine City have started, and now they need to stop it. On their way to the engine room, however, Mongul blocks their path, saying he has started the engine in order to shake Earth apart. Superman has Steel head off alone to the engine room while he personally contends with Mongul -- a fight that nearly injures Superman as Mongul gives him a bone-crushing bear hug. Supergirl offers an assist in the fight, but Mongul makes her appear by pouring machine oil on her invisible form and then just slapping her away. The fight leaves Superman nearly unconscious. Meanwhile, the Cyborg Superman is very aware of Mongul's treachery and decides to "help" Steel shut down the engine, though by materializing in the form of various cyborg-type machines, attacking Steel while giving him information about how the engine works. Realizing he is unable to destroy the fusion reactor which the engine uses, Steel knocks off the head of the Cyborg's inhabited form and uses it to jam up the engine gears, causing the engine itself to explode. Cyborg Superman reinhabits his main body, realizing that the engine is destroyed, but the Kryptonite power source remains intact. He also senses the coming of Hal Jordan and decides to let him take care of Mongul, leaving the death of Superman in his own hands.