No worse than Kasparov vs. Deeper Blue
Kasparov deliberately played some peculiar openings to get out of Deeper Blue's opening book, for the most part with success. (The main reason he lost that match was because he resigned the first game in a drawn position and played a "standard" opening in the 6th. :=)
"Beware of bugs in the above code; I have only proved it correct, not tried it."
-- Donald Knuth