Concepción, Paraguay: Brazil coach Dunga blamed a mystery virus for his team's shock Copa America exit to Paraguay on Saturday as the most successful footballing nation on the planet struggled to digest another tournament setback.

Dunga said as many as 15 members of his squad had been affected by the virus, which he said had disrupted preparations for the quarter-final against the Paraguayans.

‘I'm not making excuses, but around 15 players had viruses which limited our training,’ Dunga said.

‘Some had headaches, back pain, body aches. Some players felt it more than others and had to reduce training, some players vomited. Today was a game where we needed speed and we didn't have it,’ he added.

Dunga's explanation caused confusion amongst members of his squad, with midfielder Filipe Luis telling reporters he was unaware of any mass illness amongst his team-mates.

‘I didn't know anything about that,’ the Chelsea player said. ‘Some of the other guys might have had a problem, but I didn't.’

Goalkeeper Jefferson however backed his manager. ‘Everyone woke up with a fever, headache and body aches,’ he said, before playing down the extent to which it had affected the result.

- Brazil on sick bed? –

For the second Copa America in succession, Brazil exited at the quarter-final stage to the Paraguayans on penalties.

Dunga's side looked to be in control during the first half when Robinho fired them into a 15th-minute lead.

But Derlis Gonzalez leveled from the penalty spot for Paraguay in the second half, and then struck the winning spot-kick in the shoot-out to clinch a famous win and set up a semi-final with Argentina.

While Dunga talked about a mystery virus, others will be left asking whether Brazilian football in general is on its sick bed.

Dunga had looked to have been nursing the Selecao back to health as the team recovered from the traumatic humiliation of last year's World Cup semi-final drubbing by Germany, overseeing 10 consecutive wins in friendlies leading up to the Copa America.

But those results merely camouflaged the same problems that existed at the World Cup, a dearth of creative flair and an over-reliance on Neymar.

Brazil needed a late, Neymar-inspired goal to squeeze past Peru in their opening game, and were then derailed 1-0 by Colombia in their second match.

Neymar's frustration boiled over resulting in the four-match ban that ended his participation in the tournament. Brazil fared slightly better in a 2-1 win over Venezuela, before Saturday's loss to Paraguay.

- 'Useless to cry' –

‘We knew from the beginning it would not be easy,’ Dunga said. ‘We had many victories but we still were not happy. We will try to come back and react.

‘There's always pressure on Brazil when you win or when you lose. We will try to get better and better. Many great players have failed on penalties.

‘If it was easy a lot of people could do my job, but it's not ... It's useless to cry about it.’

Dunga meanwhile acknowledged the deeper problems facing Brazil as they attempt to reclaim their place at the summit of the global game.

‘We all have to think about Brazilian football,’ he said. ‘We can't ignore the fact that other teams have got a lot better.’

Dunga, who captained Brazil's 1994 World Cup-winning side, also called on demanding Brazilian fans to be more patient as new players developed.

‘There's a new trend in Brazil where a player plays two games and becomes a star,’ he said. ‘After two games he either becomes the best in the world or the worst in the world.’