The expanded Club World Cup has kicked off with healthy crowds, "Messi mania" and a festival atmosphere in Miami, giving an early vindication to world soccer body FIFA after fears of empty stands and global disinterest.

FIFA controversially awarded Lionel Messi's Inter Miami a back-door route into the tournament, ensuring the sport's biggest name would be there after he helped propel soccer to new heights in a country often ambivalent to the world's most popular game.

Some 61,000 fans packed the Hard Rock Stadium on Saturday to watch the Argentine and his teammates battle out a goalless, but nonetheless thrilling draw with Egyptian giant Al Ahly.

There was another strong turnout on Sunday for the clash between Paris Saint-Germain and Atletico Madrid, which ended in a one-sided 4-0 win for the Champions League winner.

However, Bayern Munich's 10-0 demolition of semi-professional Auckland City underscored the worrying gulf in quality between some of the competing clubs.

But, the opening weekend largely delivered what FIFA had been hoping for: vibrant crowds and global representation.