 The second main event resulted from events on SmackDown ! , WWE 's other main television program . In the match , Kurt Angle defended his WWE Championship against Brock Lesnar . The build @-@ up to the match began on July 31 , 2003 on an episode of SmackDown ! . During an interview promotion in the ring , Lesnar challenged Angle to a rematch of their bout at Vengeance , WWE 's previous pay @-@ per @-@ view event . The WWE Chairman , Vince McMahon , decided that Lesnar would have to earn his rematch by competing in a steel cage match against McMahon himself , and would take place on SmackDown ! the following week , with Angle officiating as a special guest referee . The Steel Cage match resulted in neither wrestler winning the match , after McMahon and Lesnar attacked Angle . On August 14 , 2003 during an episode of SmackDown ! , McMahon announced that Angle would defend the championship against Lesnar at SummerSlam . 
