Paul McCartney: Let's Go Crazy-ish Tribute to Prince

Paul McCartney stopped short of punching a higher floor when he paid homage to Prince during a concert in Minneapolis Wednesday night.

Sir Paul was playing the Target Center when he launched into "Let's Go Crazy."

Paul and his band jammed through the tune, and the crowd went nuts ... but something was missing through most of it -- Paul's vocals.

Check it out ... McCartney ain't looking for no purple bananas, but you know Prince would still dig this tribute. After all, he loved him some Beatles tunes.