Brazil and Argentina head into the second round of qualifiers for the 2018 World Cup on Tuesday looking to get their campaigns back on track after opening round defeats which have left the South American giants in disarray.

The pall of gloom enveloping Brazilian football since their humiliation against Germany at the World Cup last year darkened last week when they were humbled 2-0 by Copa America champions Chile in Santiago.

Argentina, still struggling to shake off the disappointment of losing the Copa America final in July -- the team's second defeat in a major final in 12 months -- were stunned by a 2-0 reverse at home to Ecuador.

While there is still plenty of time in South America's marathon 2018 qualifying campaign for Argentina and Brazil to turn their fortunes around, the opening defeats have left both sides determined to halt the slide.

Brazil face Venezuela on Tuesday in Fortaleza, a game that in previous years would have been regarded as a straightforward assignment against opponents who have never qualified for the World Cup.

But in a sign of how far Brazilian expectations have fallen, midfielder Willian revealed on Sunday that victory by a single goal would be viewed with satisfaction.

"To be honest 1-0 would be a good result for us," Willian said. "We want the three points. Football today is different. All the teams are fit and well trained. Maybe in the past this game would have been a sure win for us, but today it's not like that -- we only beat them 2-1 in the Copa America after all," he added.

Willian insisted that Brazil had done enough to earn a result against Chile until they were sunk by late second half goals on Thursday.

"We knew Chile would be difficult. But we marked them well for a lot of the game. We just couldn't take advantage of the opportunities we created."

Brazil badly missed the suspended Neymar against Chile, who remains banned for Tuesday's game against Venezuela.

Striker Hulk, who deputised in Santiago, said he understood the criticism of the team's attacking display.

"There is always pressure for anyone who plays as a forward for Brazil; it is our obligation because we have quality players. "We know the size of those demands and will try to answer in the best way possible," the Zenit St Petersburg striker said.

Argentina meanwhile travel to Asuncion to face Paraguay grappling a mounting injury crisis that has deprived them of their most lethal strikers. Captain Lionel Messi was already injured before the qualifiers started and Sergio Aguero joined him on the casualty list after tearing a hamstring in the defeat to Ecuador. Lucas Biglia is also out injured.

Veteran striker Carlos Tevez, who is likely to start in Aguero's absence, issued a defiant rallying cry as the two-time world champions prepared to face the Paraguayans, who will be desperate to avenge their 6-1 defeat to the Argentinians in the Copa America semi-final in June.

Tevez said the Ecuador loss was the team's worst performance since coach Gerardo Martino took over, and insisted the squad should not use the absence of Messi as an excuse.

"We are a team, and now is the moment for us to prove it," Tevez said. "Obviously it hurts us not to have the best player in the world but we will try not to notice it much; Tuesday is a chance for us to get revenge," he said.

Elsewhere Tuesday, Chile face historic rivals Peru in Lima in the latest instalment of the 'Clasico del Pacifico' while Uruguay host Colombia in Montevideo and Ecuador face Bolivia in Quito.