Why withdraw from the tournament? It's enough to ask the organizers to separate you from Britva in the bracket.
Or say, "If I get matched against Britva, I'll play with an open map."
...
I have my own idea... if the draw happens.
P.S.: I'll lose to you up to the quarterfinals, and then I'll just decline.
P.P.S.: If you have any objections to this wording, just remove me from the list of participants.