World football's rule-making body has given the go-ahead to trials for concussion substitutes which could take place at this year's Olympic Games in Tokyo.
The International Football Association Board, at its annual general meeting in Belfast on Saturday, said more research was needed before a permanent change was made to the laws of the game.
IFAB is considered the independent guardian of the laws of football.
Officials, in a statement issued after the meeting, paved the way for trials, with football one of several sports increasingly concerned by the impact of head injuries.
"The International Football Association Board (The IFAB)... agreed to draw up protocols to be used in trials for substitutions in cases of concussion," the statement said.
"The IFAB also agreed that more research data is required before proposing possible changes to the Laws of the Game.
It added: "FIFA (football's global governing body) indicated a strong interest in having trials at the men's and women's Olympic Games football tournament in July 2020, with other competitions also being able to take part in the trials."
"Often we were criticised for being slow (on concussion). Now, we move, we try, and then we'll see."