The Champions League returns this week with the first round of group-stage matches.
Here is a look at the rule changes every Manchester United, Liverpool, Chelsea and Manchester City fan needs to know as Champions League kicks off once again.
Champions League 2020/21 rule changes
When the Champions League resumed with its mini-tournament in Lisbon last season, UEFA introduced five substitutes to help reduce player fatigue.
And the rule has been extended into this year's competition.
Clubs will be allowed to name 12 substitutes on the bench for each matchday.
Managers can then introduce these subs at three different points over the course of the match.
UEFA general secretary Jonas Baer-Hoffmann said: “This is the right decision and a good first step to ease pressure on elite-level players.
“We will continue to push for further innovative ways to reduce their mounting workload and protect their health and performance.”
Matches were held behind closed doors when the Champions League resumed last season.
UEFA announced at the start of October that fans would be allowed back into stadiums for Champions League and Europa League games at a reduced capacity.
However, this can only take place in areas where local laws permit and has been capped at 30 per cent.
As it stands, fans will be able to attend Champions League matches in France and Germany.
UEFA President Aleksander Ceferin said: “Today’s decision is a sensible first step which puts fans’ health first and respects the laws in each country. While we all face a common enemy in COVID, different countries have different approaches and different challenges at any given moment. This decision allows much more local flexibility to deal with admitting fans than was previously the case, always respecting the assessment of local authorities.
“27 countries on the continent already allow fans to some extent. This decision will allow for a coherent approach on a country-by-country basis and not on a competition-by-competition basis which was sometimes difficult to understand for fans.
“In these difficult times, it is important to bring more hope and passion back into the lives of football fans and we urge them to behave appropriately and respect sanitary measures in place for their own health and for the health of their fellow club or national team supporters.”
Premier League clubs have been tearing their hair out over the new handball law and the use of VAR this season.
The new interpretation of the rule was enforced by IFAB in last season's Champions League, with Premier League being brought in line with the rest of European football this term.
Top-flight referees have also been encouraged to make more use of the pitch-side monitors, which was already the case in the Champions League.
VAR and the latest version of the handball law will feature throughout the Champions League this season, while the Europa League will have to wait until the knockout stages before VAR comes into operation.
This article was most recently revised and updated 2 years ago