MMAFighting.com's Ariel Helwani broke the news on Wednesday's edition of UFC Tonight.
Grant, the winner of five consecutive fights, was scheduled to meet Benson Henderson for the championship at UFC 164 on Aug. 31. But after suffering a concussion in training, Grant had to pull out of the fight. Pettis took his place and submitted Henderson in Milwaukee to win the title.
The card is scheduled for Dec. 14 at Sleep Train Arena in Sacramento, Calif. Grant indicated to Helwani that while he'd prefer to hold off until January to return to the Octagon, if he is formally offered the fight, he'd seriously consider accepting it.
Pettis, meanwhile, suffered a Grade 2 sprain in his left knee in his title-winning effort, but is expected to be ready to well in time for Dec. 14.
The UFC has also confirmed the evening's co-main event:Urijah Faber and Michael McDonald will meet in a pivotal bantamweight showdown. Both fighters have local ties, with Faber from Sacramento and McDonald from Modesto. Another Sacramento fighter, Chad Mendes, is expected to appear on the card, though no potential opponent has been named.