The Premier League will trial the use of concussion substitutes from February 6 in response to growing concerns about the damage caused by head injuries in football, it was announced on Friday.
Premier League and Football Association chiefs have agreed that teams will be able to make two permanent concussion substitutes even if they have made all their permitted changes.
The first match of the trial is set to be Aston Villa's home game against Arsenal on February 6.
The new rules will apply to next month's FA Cup fifth-round ties and in the Women's Super League and Women's Championship.
The protocols were approved by the International Football Association Board, the game's law-making body, last month.
The system to be used in the English competitions also allows for the opposition to make the equivalent number of changes, so that if one concussion substitute is used, they can make one change.
"The trial is a result of the IFAB's consultation with stakeholders and recommendations from their concussion expert group to allow additional substitutions for players with actual or suspected concussion," a Premier League and FA statement said.
The trial is a reaction to mounting fears about dementia cases in former players.
England and Manchester United great Bobby Charlton has been diagnosed with dementia.
Charlton's brother Jack and their fellow 1966 World Cup-winner Nobby Stiles were both suffering from dementia when they died last year.
A 2019 study carried out in Scotland found that professional footballers were three-and-a-half times more likely to die from neurodegenerative disease compared with members of the general population.
The new protocols have been criticised by consultant neuropathologist Willie Stewart, who led the University of Glasgow study, as being akin to "putting lipstick on a pig".
He, like world players' union FIFPRO, had been in favour of a 10-minute assessment period for a concussed player with a temporary substitute being introduced in the interim.
But FA chief executive Mark Bullingham said the protocol fitted well with the organisation's "if in doubt, sit them out" approach to handling concussion.
"I'm really surprised this is seen as a cop-out," he said. "I see this as going further.
"I understand there are two models that have got different values but, from our point of view, we see this as a stronger model, the safer model, and that's what we're being advised by the medical experts."
England manager Gareth Southgate has revealed he is taking part in a research project looking at possible links between football and dementia.
Southgate has volunteered to be part of the FA-backed HEADING study at the London School of Hygiene and Tropical Medicine.
"This is an incredibly important issue in our game and I'm very happy to play my part in supporting this research," he said.