A historic decision was taken by the IFAB and FIFA in March of this year, to allow for a two-year experiment which would see certain competitions allow a fourth substitution per team in extra time. The first senior FIFA tournaments that would see this amendment to the law trialled are the Olympic Football Tournaments Rio 2016, and with the knockout stages about to begin, FIFA.comtakes a closer look at how the footballing community reached this stage.

The criteria are fairly straightforward: a fourth substitute is only permitted if a match goes to extra time, and can be used whether or not the team has already used all three of their substitutes during normal time. In a pre-study survey held before the proposal was put to a vote, FIFPro consulted players, coaches and football administrators and found out that 85% of those asked were in favour of the implementation of the fourth substitution.

The IFAB granted the experimental two-year phase at its Annual General Meeting in Cardiff this year and set out some questions that needed answering in order for the trial to be a success. A detailed set of queries seek to conclude, among other things, whether the fourth substitute leads to more goals in extra time, if there is a benefit to player welfare from the fourth sub being allowed, and how often a substitute (especially the fourth substitute) scores or is significantly involved in a goal in extra time.

The evolution of the substitutionThere have been recorded substitutions throughout the history of football dating back to the late nineteenth century, after the formalisation of the game, but the first official substitutions at a FIFA World Cup™ happened at the 1970 edition. Soviet Union’s Anatoli Puzach holds the honour of being the first-ever World Cup substitute, replacing Viktor Serebryanikov against Mexico.

I would have loved to have the possibility of an extra substitution in several occasions over the course of my coaching career.

Despite the first extra time World Cup game taking place in 1934, only recently did the meeting of the two laws (extra time and the use of substitutes) enter the footballing agenda.

Carlos Alberto Parreira, who coached Brazil to World Cup victory in 1994 and is a member of FIFA's Technical Study Group (TSG) at Rio 2016, is well-placed to discuss the changing face of football after a near-50 year coaching career.

"Over the last two decades or so there have been some very crucial changes in the Laws of the Game, all of which aim at improving the quality of the game and the athletes’ welfare," Parreira said. "Adopting a fourth substitution in games that go to extra time has all the potential to be another one of these beneficial measures, since you preserve the players’ health, you increase the technical level and you open up the options for tactical variations. Myself, I would have loved to have the possibility of an extra substitution in several occasions over the course of my coaching career."

The experiment will see continuous consultation with the IFAB throughout the varying Advisory Panels and AGMs over the coming 18 months, before the final reports are prepared for presentation either at the 2018 IFAB AGM or a Special Meeting at the conclusion of the second round of experiments throughout 2017.

With the planned experiments for Video Assistant Referees beginning to take shape, a decision taken at the 2016 IFAB AGM along with the rescinding of so-called ‘triple-punishment’, the March 2016 IFAB AGM in Cardiff appears to have kicked off a period of experimentation, consultation and change in football.