RIO DE JANEIRO (AP):

Substitutes have made a big impact at the World Cup, and there could be more of them in four years' time.

FIFA's coaching advisers will propose before the 2018 World Cup kicks off that teams can use a fourth substitute in extra time.

"I think that's an idea that we will put" to football's rules-making panel, Gerard Houllier, a member of the FIFA technical study group, said at a briefing yesterday.

Up to three replacements are currently allowed, even when knockout matches go to 30 extra minutes after scores are level in regulation time.

Houllier said changing the rules could see fewer players struggle with muscle problems in high-intensity matches.

"It's a good idea. Only in extra time. Maybe if someone is injured, why not?" the former France coach said.

So far, substitutes have scored 29 goals after coming off the bench in Brazil, already a World Cup record with eight matches left to play. The previous mark was 23 at the 2006 tournament in Germany, FIFA said.