A hard blow to the head was head was suffered by a fan who forgot the cardinal rule of cricket - always keep your eye on the ball.

The spectator was taking in the New Zealand versus England cricket test at University Oval in Dunedin when he was hit this afternoon.

The painful-looking moment occurred when Black Caps batsman Hamish Rutherford hit a six over long-on. The fan was sitting on the grass bank talking to friends and appeared oblivious to the flight path of the red ball.

Sky Sport cricket commentator Craig MacMIllan described the moment to viewers: "Look out son...oh, it's a falcon. It's a painful one too. He was looking the other way and he's copped it.''

The spectator did not appear to be seriously hurt.