The lightweight match-up will likely be part of the preliminary portion of the card before the pay-per-view, which takes place on Feb. 1 at the Prudential Center in Newark, N.J.
Varner (21-8-1, 2 NC) is a former WEC lightweight champion, a title he held from 2008 to 2010. His last two UFC outings were razor-close performances that resulted in split decisions, with the most recent being a loss to Gleison Tibau, the previous a win over Melvin Guillard.
Trujillo (11-5, 1 NC) last stepped into the Octagon at the recent UFC on Fox 9 event, where he decimated Roger Bowling with a technical knockout in the second round.
UFC officials did not divulge the reason why Green was forced off the card.
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