Referee knocked out by free kick

Refereeing can be a hazardous occupation.

Whether it's rabid fans baying for blood or aggressive players lashing out over decisions.

But Argentinian whistleblower Salome Di Lorio has learned sometimes the biggest threat can be the round ball itself.

Officiating a lower grade Argentine league match between Liniers and Centro Espanol on the weekend, Di Lorio was knocked unconscious after being struck flush in the face by a free-kick.

The unlucky Di Lorio found herself in the wrong position when the kick was quickly taken and a Centro player unleashed a powerful heave from just inside his own half.

Standing less than 3m from the ball, she had no time for evasive action when the thunderbolt was struck, with the ball flooring her in an instant.

Players and officials quickly rushed to Di Lorio's aid and helped her back onto her feet before she was taken from the field and later examined at hospital.

Fortunately she escaped with no more than a headache and little memory of the incident.