According to Sherdog, which reported the replacement on Wednesday, the former lightweight champ Sherk recently suffered a shoulder injury while training that will sideline him for approximately four weeks.
Neer (25-8-1) has alternated wins and losses since returning to the Octagon last year, picking up wins over Din Thomas and Mac Danzig while dropping a split decision to Nate Diaz last September as well as a hard-fought unanimous decision to Kurt Pellegrino early last month at UFC 101.
Tibau (17-6), 5-4 since joining the UFC in late-2006, holds wins inside the Octagon over Jason Dent, Jeff Cox, Terry Etim, Rich Clementi, and Jeremy Stephens while losing bouts to Nick Diaz, Tyson Griffin, Joe Stevenson, and Melvin Guillard. He had won back-to-back fights over Clementi and Stephens, before losing to Guillard in his most-recent bout in June.
Late last month, the matchup between Sherk and Tibau was shifted from the UFC 103 prelims to the UFC 104 main card, but Neer-Tibau is likely to be demoted to the undercard and replaced by Ryan Bader vs. Eric Schafer or Yushin Okami vs. Chael Sonnen on the pay-per-view broadcast.