UEFA on Thursday confirmed managers will be able to make up to five substitutions in Champions League and Europa League games this season.
This means Liverpool and Manchester United will be able to make more than the usual three substitutions for the first time.
Manchester City and Chelsea previously benefited from the rule in last season's Champions League knock-out stages.
United also benefited from the rule change as they reached the Europa League semi-finals, but they have never made more than three substitutions in the regular 90 minutes of a Champions League match.
UEFA have now ratified the rule change for numerous competitions under their jurisdiction for the 2020/2021 campaign.
A statement from the governing body reads: "The UEFA Executive Committee also decided to allow up to five substitutions for all matches played in the UEFA Nations League, the European Qualifiers play-offs, the UEFA Women's EURO Qualifiers, the UEFA Champions League and the UEFA Europa League as from the group stage, and the UEFA Women's Champions League, for the remainder of the season, in order to alleviate the burden on players caused by the condensed 2020/21 international match calendar amid the Covid-19 pandemic."