ESPN.com has confirmed with UFC officials that the matchup has moved to the main portion of UFC on FX 5 set for Oct. 5 in Minneapolis.
The entire UFC 151 event, scheduled to take place Sept. 1 in Las Vegas, was scratched Thursday.
A main event title bout between 205-pound champion Jon Jones and Dan Henderson fell through when Henderson suffered a knee injury while training. The card ultimately was eliminated when Jones turned down an offer to fight Chael Sonnen as a replacement.
Ellenberger (27-6) originally was scheduled to meet Josh Koscheck, but that fight fell through because of a Koscheck injury. The Nebraska-based Ellenberger had a six-fight win streak snapped in June, a TKO loss to Martin Kampmann.
Hieron (23-5), who replaced Koscheck on short notice, was looking forward to his return to the UFC. The veteran welterweight last competed in the Octagon in October 2005. He's since fought for several promotions, including the IFL, Strikeforce and Bellator Fighting Championships.
The two welterweights previously met with Hieron handing Ellenberger his first professional loss via unanimous decision at an IFL event in June 2006.