Duffy pulled out of the contest with an injury, while Poirier declined a last-minute replacement, forcing both lightweights off that card.
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Duffy and Poirier, who were replacing Stipe Miocic and Ben Rothwell, were themselves replaced by Patrick Holohan and Louis Smolka.
UFC 195 takes place January 2nd at the MGM Grand Garden Arena. Welterweight champion Robbie Lawler defends against former interim champion Carlos Condit.