Cheeky Robbie Williams has shown off his impressive physique by stripping naked on his 41st birthday on Friday (13Feb15).

Wearing nothing but a wristwatch, a necklace and a grin, the tattooed former Take That star offered fans a glimpse of what he sees in his bathroom mirror when he posted a naked full frontal shot of himself on Instagram.com.

Cupping his hands over his genitals, Williams showed off an impressive six-pack as he posed for the camera.

His birthday surprise comes less than a week after Williams posted another naked shot online and called himself a "naturist", adding, "I enjoy nakedness. I am a bit of a naturist at heart. What about you?"