An injury has forced Sean Pierson to pull out of his UFC 158 bout against Rick Story and Quinn Mulhern will now replace Pierson in the bout. 
UFC officials have announced the change after it had been reported previously and the fight will take place on the preliminary card on FX.
Mulhern (18-2) comes to the UFC via Strikeforce and this will be his debut in the UFC. He lost his Strikeforce debut to Jason High by decision and won his next three fights in the company, with two of the wins coming by decision.
Story (14-6) won six of his first seven fights in the UFC, but has lost three of his last four. After snapping a two fight losing streak to Brock Jardine, he took on Demian Maia at UFC 153 and was defeated in the first round by submission.
UFC 158 takes place on March 16th from the Bell Centre in Montreal and will be headlined by Georges St-Pierre defending the UFC welterweight title against former Strikeforce welterweight champion Nick Diaz.