"Well, I really have changed a lot, haven't I? The clothing's improved..." he said, observing him closely. "Yes... I can tell you who I am, but first... Where is your TARDIS and why are you trying to get into mine?" he asked.
He whipped out the sonic screwdriver from his inside jacket pocket and proceeded to quickly scan the other Doctor. He held the device upright and peered closely at the readings before looking back at his younger self, screwdriver still held up.