Gerard Butler ROCKS OUT Manhattan Club … with Help from Oasis [VIDEO]

It hasn”t been 2 months since Gerard Butler left rehab for substance abuse — but last week, he was already back at an NYC bar, where he blew away the crowd with a knockout performance of “Wonderwall” … and we got video!!!

Butler stopped by The Darby supper club in Manhattan last Thursday — the actor didn”t drink a drop … but he did take the stage and perform several songs, including one by The Doors and another by The Rolling Stones.

But the best by far … Butler”s rendition of the Oasis classic “Wonderwall” — you gotta check out the clip. After all.