Who will it be? --- Day 3/122

Walk: Union Square
Distance: 6 blocks and then in from the heat

                                        Ken Jennings                    Brad Rutter
This the last semi-finals night for the Jeopardy $1,000,000 Battle of the Decades.  So far the biggest Jeopardy all time winners have made it.  Last time they met again, they played against Watson, IBM's computer: 

Who will they play against now?  I'm guessing either:
                       OR            
   Roger Craig                                 Colby Burnet