Football's lawmakers have approved a temporary rule change that will allow each side up to five substitutes per match while opening up the prospect for the controversial VAR system to be suspended.
Proposals to allow an additional two substitutes were put forward by Fifa in order to protect player welfare when football resumes amid the coronavirus pandemic, and the International Football Association Board (IFAB) have given the idea an immediate green light.
The IFAB - which is made up of the four British associations and world governing body Fifa - say each side will have only three opportunities, excluding half-time, to make changes in an amendment which will be allowed in all competitions that finish before the end of 2020.
All major European leagues have been suspended for several weeks but a number are still hoping to complete the 2019-20 season, which will almost certainly involve fixtures being crammed into a slim time-frame.
A Fifa statement said: "As football begins to consider resumption of competitions across the world following the Covid-19 pandemic, the International Football Association Board (The IFAB) have agreed to make a temporary amendment to the laws of the game based on a proposal received from Fifa seeking to protect player welfare.
"For competitions which have either started or are intended to start, but are scheduled to be completed by December 31, 2020, the IFAB have approved Fifa's proposal to introduce a temporary amendment to Law 3 - The Players, which will allow for a maximum of five substitutes to be made per team.
"However, to avoid disruption to the game, each team will only have three opportunities to make substitutions; substitutions may also be made at half-time.
"The temporary amendment comes into force with immediate effect, and has been made as matches may be played in a condensed period in different weather conditions, both of which could have impacts on player welfare.
"The decision on whether to apply this temporary amendment will remain at the discretion of each individual competition organiser."
VAR was introduced in the Premier League at the start of the 2019-20 season but has been widely criticised amid a plethora of controversial decisions.
Fifa say the system could be discontinued upon football's restart but that decision would rest with each competition's governing bodies. If it remains, usual rules regarding VAR apply.