Argentina are playing far below their best, are over-reliant on Lionel Messi and must improve if they are to beat Belgium in their World Cup quarter-finals, according to Diego Maradona.

"We still haven't got started," Maradona, who won the 1986 World Cup with Argentina, said in a withering analysis of the team's performances so far at the tournament in Brazil.

"They need to get it into their heads that we can't be 'Sporting Messi'. Maybe he can score a great goal ... but if it doesn't come off for the kid, we can't jump on him tomorrow as if he's guilty of the Argentine disaster."

Maradona, Argentina's coach at the last World Cup where they went out in the quarter-finals, was speaking on Venezuelan TV after Argentina's defeat of Switzerland this week. His comments were widely reported in Latin American media on Thursday.

He said Argentina's big name team were playing at only 40 percent of their capacity and criticized them for only squeaking past Switzerland 1-0 with a last-gasp goal in extra time.

"Man-for-man, and collectively, Argentina are better. They (the Swiss) may make good watches but they have few footballers," the always controversial Maradona said.

Argentina, who were to train behind closed doors on Thursday at their camp in Belo Horizonte before flying to Brasilia for Saturday's game versus Belgium, won all three group games before beating the Swiss in the last 16.

Messi has won man-of-the-match in each game, and scored four of Argentina's seven goals. But the wins have all been by one-goal margins and have masked some subdued individual performances by other players expected to make bigger contributions.

"The kid [Messi] is very alone ... The team doesn't have a change of rhythm, movements in its strikers," added Maradona, saying the players lacked a give-it-all attitude.

"I feel something very strong inside, like bitterness, rage, frustration, because Argentina can play much, much better ... The coach has to impose this." If they do not improve against Belgium, "we're in trouble," he said.

Argentina have won the World Cup twice and would dearly love to lift it for a third time on the soil of their great rivals Brazil. Tens of thousands of blue-and-white-clad Argentines have flooded across the border to cheer them on.