UFC officials announced the change Thursday. The 170-pound fight will still headline the event, which takes place at Consol Energy Arena in Pittsburgh.
Story (13-3) is riding a six-fight win streak, including high profile wins over Alves and Johny Hendricks. His only loss under the UFC banner came via unanimous decision to John Hathaway in his promotional debut in June 2009.
Marquardt (31-10-2), a former No. 1 contender at middleweight, announced his interest in dropping a weight class following a unanimous decision win over Dan Miller at UFC 128 in March. The Denver-based fighter is 2-2 in his last four fights, but is still ranked the No. 5 middleweight according to ESPN.com.
In the only UFC title fight of his career, Marquardt suffered a first-round TKO loss to Anderson Silva in July 2007.
Brett Okamoto covers mixed martial arts for ESPN.com.