UFC President Dana White announced the move on Thursday afternoon via Twitter.
After missing a required press conference for his UFC 137 headliner against welterweight champ Georges St-Pierre on Wednesday, Diaz was removed from the title fight and replaced by Penn’s original opponent, Carlos Condit.
Diaz (25-7) is returning to the Octagon on an 11-fight win streak after defending his Strikeforce title over UFC veteran Paul Daley in April. Penn (16-7-2) rebounded from a pair of losses to lightweight champion Frankie Edgar with a 21-second KO of Matt Hughes in November before fighting Jon Fitch to a draw in February.
UFC 137 takes place on October 29 in Las Vegas, Nevada and will be headlined by the aforementioned UFC welterweight title fight between UFC welterweight champion Georges St-Pierre and former WEC champion Carlos Condit.
Stay tuned to MMAFrenzy.com for updates on Penn’s opponent and complete UFC 137 coverage.
Pictured: Nick Diaz