The 32-year-old is hopeful his side can inflict a second successive defeat on the Blaugrana on Thursday in the Copa del Rey
It will be the third time in less than two weeks that the two team's have met, with the tie finely poised at 2-2 after last week's first-leg clash at Camp Nou.
And the Argentine, whose side lost 3-1 in their Liga game against the Blaugrana, admitted he has been encouraged after Barcelona suffered a shock defeat at Real Sociedad on Saturday.
“As is the way with football, this same weekend Barcelona showed that they are not an invincible team and that even they can lose a two-goal lead," Demichelis told reporters.
"We have shown that in difficult situations and tough games that we are up for it. In football you never know, they might arrive angry and then it will be difficult to deal with them.
"Hopefully some doubt arises in them, though I do not think so because they are used to setting out to win every two or three days. Being able to eliminate Barcelona would be something with global significance."
Meanwhile, Malaga boss Manuel Pellegrini has lamented the playing surface at La Rosaleda ahead of hosting the defending champions.
“It’s worse than ever," said the former Real Madrid coach.
"It is more than difficult to walk on. It does not affect just one or two players, [it affects] all of us, with rubber studs [and] aluminium."