Standoff at the Glass

I found a rectangular mirror resting vertically against the baseboard. Inside the glass, an exact duplicate stood facing me. I squared my stance and raised my right arm into a defensive guard. He responded instantly, matching my posture angle for angle. I took two deliberate paces forward and delivered a direct thrust with my fist. My knuckles struck the glass with a sharp, solid tap. His fist met mine at the exact same split-second, halting my advance entirely. We held the contest for five seconds without either side giving ground. An evenly matched opponent.