Argentina legend Diego Maradona says the team's draw with Iceland was a "disgrace" and warned manager Jorge Sampaoli "he can't come back to Argentina" playing like that.
Lionel Messi missed a penalty as his side were surprisingly held by debutants Iceland in their opening Group D game on Saturday.
Maradona, a former national team coach, watched on at the Spartak Stadium.
"I get the feeling there's an anger at the heart of the team," he said.
Argentina took the lead through Sergio Aguero in the 19th minute but Iceland, playing at their first ever finals, levelled four minutes later through Alfred Finnbogason.
"It's a disgrace. Not having prepared for the match knowing that Iceland are all 1.90m tall," the 1986 World Cup winner told Venezuelan television.
Messi was looking to match the impact his old rival Cristiano Ronaldo has made on the tournament - the Portuguese scored a sensational hat-trick against Spain on Friday night.
But his 63rd-minute spot kick was saved by Hannes Halldorsson and he struggled to break down a well-organised Iceland defence.
"I don't blame the players. I could blame the lack of work rate. But I can't blame the players, much less Messi, who gave it all he had," said Maradona.
"I missed five penalties on the spin and I was still Diego Armando Maradona. I don't think that they dropped two points because Messi missed a penalty," added the 57-year-old, who led Argentina to the quarter-finals in South Africa in 2010.
Argentina play Croatia in their next game in Saint Petersburg on 21 June.