The promotion doesn't know when Grant will return to the Octagon, and after Saturday's UFC 166 card, UFC president Dana White said that when Grant does come back he might not be fighting for the title:
T.J. Grant's in one of those unfortunate situations where he's had a title shot, and he had to pull out twice, so he might have to come back and fight another fight, we have to keep this thing rolling. It's (Melendez's win) a huge step back for T.J. Grant
One of the main reasons behind White's comments was the bout between Gilbert Melendez and Diego Sanchez that took place on Saturday. The three round battle will be under strong consideration for 2013's Fight of the Year, and it solidified Melendez's ranking as one of the top fighters in the division.
If Thomson upsets Pettis in December, expect the UFC to book Thomson versus Melendez. The two fought three times in Strikeforce, with Melendez winning two of those three. If Pettis scores the win over Thomson, don't be surprised to see the UFC book Pettis versus Melendez.