Disgruntled Premier League managers could ask for the return of the five substitutes rule this season, despite the concept twice being rejected.
A growing number of managers are not happy they can only make three substitutions in 2020-21, after being allowed five when last season resumed.
The Premier League is the only major competition to return to three.
Some leading managers believe the current substitution limit is contributing to injury problems.
Liverpool boss Jurgen Klopp and Manchester City counterpart Pep Guardiola have both said the decision is partly responsible for a spate of muscular injuries across the top flight.