paragraph: In 1989 , Kevin Flynn , software engineer and the CEO of ENCOM International , disappears .  Twenty years later , his son , Sam , now ENCOM's primary shareholder , takes little interest in the company beyond playing an annual trick on the board of directors ; but is requested by his father's friend , ENCOM executive Alan Bradley , to investigate a message originating from Flynn's shuttered Video arcade .  There , Sam discovers a hidden basement in Which Sam unintentionally teleports himself to the Grid , a virtual reality created by his father .  On the Grid , Sam is sent to compete against a masked program called Rinzler who , having realized that Sam is a human User after seeing him bleed , takes him before CLU , an alter ego of Kevin Flynn who rules the Grid .  CLU nearly kills Sam in a Light Cycle match ; but the latter is rescued by Quorra , an `` apprentice '' of Flynn's , who conveys him to his father outside CLU's territory .  There , Flynn reveals to Sam that he had been working to create a `` perfect '' computer system and had appointed CLU and Tron its co-creators .  During this construction , the trio discover a species of naturally-occurring `` isomorphic algorithms '' , not conceived by Flynn , bearing the potential to resolve various mysteries in science , religion , and medicine .  CLU , having deemed them an aberration , betrayed Flynn , captured Tron , and destroyed the ISOs .  Meanwhile , the `` I/O portal '' permitting travel between the two worlds had closed , leaving Flynn captive . 
question: What nearly kills Sam in a Light Cycle match?
answer: CLU