Chelsea coach Enzo Maresca labelled the atmosphere in his team's opening Club World Cup game on Monday "strange" after the Blues triumphed in front of nearly 50 000 empty seats.

The Uefa Conference League winners defeated Los Angeles FC 2-0 at the Mercedes-Benz Stadium in Atlanta with only 22 000 fans present at the 71 000-capacity arena.

"The environment was a bit strange, the stadium was almost empty, not full," Maresca told reporters.

"We are professional, we have to adapt to the situation, to the environment...

"It's important the behaviour of the players, the attitude, and once again they showed how professional they are."

The Chelsea coach said his team had expected a larger crowd, but were hopeful they would get that in their second game against Flamengo of Brazil in Philadelphia.

"We prepared this game also thinking that the environment was a bit different, but no doubt that the next one will be a nice one, because we know that the Brazilian teams, they always bring many, many fans," he added.

Over 60 000 spectators attended the opening match between Lionel Messi's Inter Miami and Al Ahly on Saturday, while 80 000 were present at the Rose Bowl in Pasadena on Sunday for the clash between Uefa Champions League winners Paris-Saint Germain and Atletico Madrid.

Plenty of Boca Juniors fans created a raucous atmosphere later on Monday for their match against Benfica at the Hard Rock Stadium in Miami.

With Chelsea playing at 3:00 pm local time on a working Monday, the Mercedes-Benz Stadium was under a third full.

MLS side Atlanta United average nearly 45 000 fans at their matches and are the best supported US team.

"PSG against Atletico, in front of a big crowd at the Rose Bowl...so I don't know if there's just more fans in Los Angeles who are into this tournament than here, or if it's the pairing tonight," said LA coach Steve Cherundolo.

However the American said it was too early to judge Fifa's new expanded competition on the basis of just one match.

"Regarding crowds I think it's kind of different each game you look at, so I don't think we should be talking about this right now," he added.

"I think we should wait until the end of the tournament...(to make) an opinion about it as a whole, as opposed to one game."