The following is an article from UFC.com:
Knee Injury KO's Drwal from UFC 81
Thomas Gerbasi, UFC – A knee injury has forced light heavyweight Tomasz Drwal to withdraw from his February 2nd bout with David Heath on the UFC 81 card in Las Vegas. No replacement will be made for this fight, and UFC 81, which is headlined by the interim UFC heavyweight title fight between Tim Sylvia and Antonio Rodrigo 'Minotauro' Nogueira, and the UFC debut of Brock Lesnar against Frank Mir, will carry on with eight bouts.
