Germany's national team manager says FIFA's plan to increase the World Cup to 48 teams could "dilute" the sporting value of the competition.
Joachim Löw has voiced his opposition to any further expansion of international football tournaments.
The 2016 European Championship in France saw the number of participating teams increased from 16 to 24 and new FIFA president Gianni Infantino would now like to see the number of World Cup participants increased from 32 to 48.
Some critics lamented a decrease in the quality of football at this summer's European Championship and German national team coach Löw has warned that the sport's governing body risks a similar "dilution” at the World Cup.
"World Cups and European Championships should feature the best teams," he said on Wednesday in Hamburg.
"When you keep increasing the number of teams, you dilute the quality. In my opinion, from a sporting perspective, the tournament is perfect with 32 teams."
Löw also questioned the political motives behind such an expansion, suggesting that Infantino is hoping to appeal to the numerous small football associations which make up FIFA and which all command equal votes but whose national sides rarely qualify for the World Cup finals.
Indeed, Infantino owes his election as Joseph Blatter's successor to a manifesto pledge to increase the number of World Cup participants to 40. This has now been increased to a total of 48 to allow for a play-off round featuring 32 teams with the 16 victors joining 16 seeded teams in the group stage.
Speaking to German newspaper Welt am Sonntag at the weekend, Löw did recognize that the expansion plans do "open up the path for smaller nations to take their place on the big stage.”
But the 2014 World Cup winning manager also warned that expanded summer tournaments place added mental strain on players who already have to deal with a busy schedule during the regular season.
"We must be clear that the quality [of football] could suffer in the long term,” said the 56-year-old. "We must be careful not to overdo it.”
German football league (DFL) president Reinhard Rauball already expressed his opposition to an expansion of the World Cup in an interview with Sport Bild in September.
"Both the DFB and the Bundesliga are against an expansion of such tournaments which would impact negatively on players, clubs and fans,” he told the German magazine.
The new format is due to be discussed at the next meeting of the FIFA Council in Zurich on the 13-14 October, where the idea of a regional World Cup will also make the itinerary.