Anthony Martial was substituted in the 38th minute at Watford. Nick Potts / PA Wire/Press Association Images

Brain injury charity Headway has called for an independent review of football's approach to concussions following an incident involving Manchester United striker Anthony Martial in Sunday's 3-1 defeat at Watford.

The France international appeared to be concussed after a clash of heads with Watford defender Daryl Janmaat in the 27th minute of the Premier League match.

Seven minutes later, a groggy-looking Martial lost the ball in the build-up to Watford's opener and four minutes after that he was substituted.

Headway's spokesman Luke Griggs told Press Association Sport that the charity was not specifically questioning United's treatment of Martial but it was deeply concerned about the general application of the concussion rules football introduced in August 2014.

Those rules were brought in after several high-profile incidents that attracted considerable criticism of football's attitude to head injuries and they stipulate that all home teams must employ a third "tunnel doctor" to help team doctors identify concussions and decide whether the player is fit to continue.

They also reinforced the Football Association's protocol that a player should even be removed if a concussion is only suspected, but not necessarily confirmed -- what Headway refers to as the principle of "if in doubt, sit it out."