Numerous players and coaches, including England captain Harry Kane, have voiced concern over player welfare with the revamped Club World Cup meaning less time off between seasons.
The revamped Champions League will feature a tennis-style seeding system for the last-16 knockout phase, UEFA said.
FIFA also announced a newly structured international calendar which its president Gianni Infantino said had been endorsed by the ECA.
UEFA president Aleksander Ceferin said they were committed to "qualification based on sporting merit".
The analysis by the European Club Association (ECA) also warned that the biggest losses would be felt next season, even if it is played in full.
The ECA, an organisation representing 220 soccer clubs, opposes the world governing body's decision which Rummenigge, the former Germany international who is also Bayern Munich's chief executive, has previously dismissed as "nonsense".
World governing body FIFA said it had made progress on streamlining the international match calendar on Monday, saying it would recommend a UEFA-backed plan that would abolish unpopular international friendlies in August.
'We had already started thinking about how to set a new calendar from 2024, now with this crisis we need immediate answers'
CAS ruled that City did not breach financial fair play rules by disguising equity funding as sponsorship, but imposed a 10 million euro fine for failing to cooperate with UEFA.
UEFA will share 100 million euros among the clubs who released players for the Euro 2012 soccer finals and qualifying competition, the European Clubs Association (ECA) said on Tuesday.
Belgium's Pro League on Thursday cancelled the remainder of the season, which has been suspended from last month because of the coronavirus pandemic.
Europe's top clubs have won concessions from UEFA over the implementation of new rules designed to tighten up football's finances, Karl-Heinz Rummenigge said on Tuesday.
FIFA president Sepp Blatter said that clubs must release their eligible Under-23 players for the Olympic soccer tournament.
News of all that transpired on and off the football field
News of all that's transpired on and off the football field
FIFA president Gianni Infantino has said that football will be "totally different" when it re-starts after the coronavirus. He has talked of smaller, but more meaningful, competitions, more balance and football being "more attentive to true values."
News of all that's transpired on and off the football field
European clubs are anticipating another windfall after changes to the Champions League and say the new system will be fairer as well as making them richer. The European Clubs Association (ECA) said it expected revenue from the Champions League and Europa League to jump from 2.35 billion euros ($2.62 billion) per season to around 3 billion euros from 2018-19, when the changes, announced by UEFA last month, come into force. ECA chairman Karl-Heinz Rummenigge also ruled out talk of a breakaway Super League in the foreseeable future, saying the clubs wanted to remain united.
FIFA has reportedly raised objections of holding the 2022 Qatar World Cup in the summer in light of health risks and speculations are that the tournament would be held in winter.
FIFA president Gianni Infantino is planning a fresh 24-team Club World Cup to start with a 'pilot' edition in 2021.
News of all that's transpired on and off the football field.
FIFA ended more than four years of uncertainty over the timing of the 2022 World Cup in Qatar by announcing on Thursday that it would be played in November and December with the final on December 18.
This and more from the happenings in the world of football
La Liga has taken legal action against 10 people who allegedly threatened Ukraine international Roman Zozulya following his move to Rayo Vallecano last week, the Spanish league said in a statement on Thursday.
FIFA announced that clubs will not get compensation for losing players and suffering domestic disruption due to a 2022 winter World Cup in Qatar.
FIFA president Gianni Infantino said a wind of change was blowing through football's scandal-plagued world governing body after announcing a sponsorship deal with China's Wanda Group on Friday.
News of all that's transpired on and off the football field
News of all that's transpired on and off the football field
News of all that's transpired on and off the football field
News of all that's transpired on and off the football field
Despite widespread speculation that FIFA will vote to switch the dates of the 2022 World Cup on Friday, soccer's world governing body will probably delay making a decision and instead set up a task force to analyse the huge implications of moving the tournament from the searing heat of the Middle East summer.
International Ski Federation (FIS) president Gian-Franco Kasper has warned FIFA against holding the 2022 World Cup in Qatar at the same time as the Winter Olympic Games.