From 2018/19 season, the top four European leagues -- currently Spain, Germany, England and Italy -- will each be guaranteed four places in the group stage, UEFA competitions director Giorgio Marchetti told reporters.
Stung by criticism that the competition has become too predictable, UEFA emphasised that it would continue to be open for teams from Europe's smaller national leagues although the number of places set aside for them would drop from five to four.
Europe's top clubs had discussed the possibility of forming a breakaway Super League but UEFA's acting general secretary Theodor Theodoridis played down the threat.
"From the very beginning, the feeling was the ideal solution for everybody would be a solution in the family," he told reporters. "We spoke to everyone...the feeling we had was that they always wanted to stay."
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UEFA also stopped short of guaranteeing captive places for certain big clubs, another possibility which sources said had been discussed privately in meetings over the past few months.
Under the present system, the top three leagues have three places each while their fourth-placed teams must play off over two legs for a place in the group stage.
The fourth ranked league, currently Italy, have only two guaranteed places plus one in the playoff round.
UEFA uses a complicated coefficient to determine the rankings of the national leagues.
Marchetti said the format itself would remain the same with a qualifying stage, followed by a 32-team group stage and then a knockout contest.
The champions and runners-up of the fifth and sixth-ranked leagues, at present France and Russia, will continue to have two places while the champions of the seventh to 10th ranked leagues, currently Portugal, Ukraine, Belgium and Turkey, will also qualify automatically.
The biggest losers were the 11th and 12th ranked leagues, currently Switzerland and the Czech Republic, who will lose their guaranteed places in the group stage.
Instead, they will now compete in a qualifying competition with national champions from all other European leagues for four places in a qualifying competition played in July and August.
Theodoridis said it was an achievement just to keep any places for teams from the smaller leagues who struggle to compete on level terms with the elite clubs.
"We started this process by having one target, keeping the dream alive having all national associations having access," he said.
UEFA has been without a president since last December when Frenchman Michel Platini was banned for eight years by global soccer body FIFA for ethics violations, later reduced to four on appeal by the Court of Arbitration for Sport (CAS).
UEFA will hold an election to find a replacement for Platini in Athens on September 16. Michael van Praag, Angel Maria Villar and Aleksandar Ceferin, the heads of the Dutch, Spanish and Slovenian federations respectively, are the three candidates.
(Writing by Brian Homewood; editing by Amlan Chakraborty)
