Vinícius Júnior criticised the Copa América's pitches, referees and organisers CONMEBOL after putting in a player-of-the-match performance in Brazil's 4-1 win over Paraguay on Friday.

The Real Madrid forward scored twice in a convincing win at Allegiant Stadium, Las Vegas, to leave Brazil on four points in second place in Group D -- behind leaders Colombia -- and on track to qualify for the quarterfinals.

"The Copa América is always difficult because of the pitches, because of the referees -- who always go against us -- and because of the way CONMEBOL treats people," Vinícius said post-match. "It's always difficult, but we have to stay strong. We can only talk by winning. When we talk, CONMEBOL say we talk too much."

ESPN has approached CONMEBOL for comment.

Brazil had an underwhelming start to the competition, drawing 0-0 with Costa Rica on Monday, with Vinícius coming in for criticism and questions over his role in the team.

However coach Dorival Junior hailed the forward as "almost perfect" after his display against Paraguay.

"I played a great game today, in line with the level of player I am," Vinícius said.

Opponents Paraguay were less impressed.

"[Vinícius] has a way of playing which is not easy for opponents to accept," coach Daniel Garnero said. "That's why the referee is there. The referee has to impose those limits."

The state of pitches at the Copa América -- with natural grass being laid on top of artificial turf at six of the venues -- has been frequently discussed at the tournament so far.

Argentina coach Lionel Scaloni criticised the quality of the surface at Mercedes-Benz Stadium, Atlanta after the opening game there, saying it was "not suitable for this kind of players" and goalkeeper Emiliano Martínez calling it "a disaster."

On Saturday in Group A, champions Argentina -- who have already qualified for the quarterfinals -- play Peru in Miami, Florida, while Canada play Chile.