Arturo Vidal believes that his Chile side are equipped to knock Spain out of the World Cup.
The defending champions were routed 5-1 by the Netherlands in their opening Group B fixture and will face Chile on Wednesday June 18 in the Maracana.
Vidal's side defeated Australia in a pulsating encounter in Cuiaba on Friday night to move level with the Dutch on points and Jorge Sampaoli's men now face a crucial second game against the holders.
If the Spaniards are defeated then their World Cup defence will end after only two matches, and the Juventus midfielder believes that Chile are up to the challenge after goals from Alexis Sanchez, Jorge Valdivia and Jean Beausejour downed the Socceroos.
"Spain will have watched our game today," Vidal told Goal. "They know it will be always difficult for them to play against us."
Chile raced into an early two-goal lead with Sanchez right at the heart of the action. He fired Chile ahead with a smart finish following strong play by Charles Aranguiz before laying on an assist for Jorge Valdivia's brilliant contribution.
The South Americans threatened at that stage to overwhelm the Socceroos but a moment of laxity brought the underdogs right back into the game.
An Ivan Franjic cross was met by a characteristic Tim Cahill header, who left Claudio Bravo with no chance. Cahill could have levelled moments later when Matthew Leckie found him with a through pass but Bravo was equal to the task on that occasion.
Australia had the better of the chances thereafter, if not all the play, and Chile in the second half had Bravo to thank for ultimately preserving all three points.
"It was a very difficult game," Vidal admitted afterwards.
The threat of Sanchez on the break remained throughout and he occupied the Australian defence with his ability to turn quickly and find passes behind the lines.
On one occasion in the second half, his dexterity won him space away from the Aussies and he slipped a hidden pass into the path of Eduardo Vargas. The Valencia man's effort was goal-bound but tame and Alex Wilkinson was able to clear off the line before the goal-line technology system was needed.
Chile finally quenched the Australian challenge in injury time when Jean Beausejour struck a left-footed shot across Mat Ryan for 3-1.
Vidal played the best part of an hour in his comeback from knee surgery which limited his participation in Chile's build-up to the tournament. The Juventus midfielder is confident that his knee will stand up to the rigours of tournament football.
"The knee is fine," he said. "Every day I give everything so I am able to play."