Saturday's final between Manchester United and Barcelona at Wembley is set to be the most lucrative in European club football history, boosted by the clubs' strong brands, the latest annual MasterCard survey said.
It could be worth 369 million euros to the clubs and countries involved, a rise of five percent on last year.
But the rate is a slowdown on previous finals, indicating the European market may have become saturated, and that UEFA will have to look to new markets such as the emerging economies, south and central America and BRIC countries for future growth.
The presence of a British team in the MasterCard-sponsored final was likely to have contributed to the dip.
"Europe is a mature market, and I think medium-to-long term, maybe UEFA has to look towards other markets across the world for continuing and sustained growth," the author of the report, Professor Simon Chadwick, told reporters.
Manchester United, which last week won the English Premier League, play Spanish champions Barcelona in a re-run of their 2009 final in Rome, won by the Catalan club.
Up to 220 million television viewers are expected to watch the world's most high-profile clubs battle it out, each hoping to lift the cup for the fourth time.
The winning team can expect to earn a windfall of 126 million euros, up five percent on last year, but down on the nine percent rise the year before. The losing finalist could hope to pick up 73 million euros, a rise of 4.3 percent on last year, but lower than the 7.7 percent the year before.
The economic downturn was one of the reasons for the slower growth, while more refined data could be another, Chadwick said.
London can expect to generate 52 million euros from hosting the game, a four percent rise on Madrid last year.
It should further bolster the capital's reputation as one of the world's most sporting cities, especially ahead of the 2012 Olympics, but the figure is less impressive than the 11 percent generated by Madrid on its predecessor, Moscow.
"In terms of the British economy ideally it would be two foreign clubs," Chadwick told Reuters.
"That is one of the reasons why the figures have not been quite so ostentatious perhaps as in previous years. They have been a little more cautious because effectively these people are coming down from Manchester rather than people coming from Munich, Lyon or anywhere else."
Switching the final to a Saturday has had positive results, but it has yet to fully bed down with fans, Chadwick said.
David Taylor, chief of UEFA events, told Reuters there was "no reason to believe we will change" back to Wednesdays, when it reviews the situation next year.
When asked if he could ever see a Champions League game being held outside Europe, he said: "The business logic may take you there but the sporting logic does not. So the answer would be 'no.'"
UEFA has been criticised for Wembley tickets costing up to 4,680 pounds, making it the most expensive club game in history.
Taylor repeated UEFA President Michel Platini's comment that maybe it had not been the smartest decision it had ever made, and that it will consider a reduced price category in future.
"Football is a game that we can't price people out of completely," he said, noting however that the game was a sell-out.