Axl Rose In Studio with AC/DC!!

No one on the planet is about to rock as hard as Axl Rose, and we have the first photos of him leaving rehearsing with what could be his new band ... AC/DC!

There are reports the Guns N' Roses frontman is going to fill in as lead singer for AC/DC, which is rumored to be opening for GNR on its upcoming tour. Axl was at a rehearsal studio in Atlanta with Angus Young and co. on Friday ... maybe running through the classics, maybe finalizing a deal.

Neither side's reps are confirming anything yet.

Looks like Axl's been working hard to get in shape for the double duty tour -- and this is our first look at him in a long time.

If the voice works ... do ya really care what he looks like?