Lesnar successfully defended his newly won title against the debuting Paul London on October 9 edition of SmackDown ! . He returned to feuding with The Undertaker . Lesnar had previously cost Undertaker the title in a match against then @-@ champion Kurt Angle , which granted him a shot at Lesnar 's title . At No Mercy , Lesnar defeated Undertaker in a Biker Chain match . The rivalry then came to an end after The Undertaker chose to focus on Mr. McMahon .