Pettis (17-2 MMA, 4-1 UFC) will be sidelined for the next seven to eight weeks with a Grade 2 knee sprain, which in medical terms is considered a "moderate" sprain. UFC President Dana White broke the news Tuesday night on ESPN's "SportsCenter," and UFC officials later announced it, as well.

When Pettis is able to return following the rehab for the knee injury – which will not require surgery – he won't be taking a superfight with featherweight champion Jose Aldo. Instead, he'll fight top contender T.J. Grant (21-5 MMA, 8-3 UFC).
http://www.mmajunkie.com/news/2013/0...rant-on-return

Good