Along with hosts and holders Qatar, and Iran, Iraq were one of only three teams to reach the knockout rounds with a 100 percent record.
That included defeating pre-tournament favourites Japan 2-1, raising hopes back home that Iraq can repeat their fairytale 2007 Asian Cup triumph.
But their Spanish coach Casas on Sunday attempted to play down their title chances, starting against Jordan.
"If we give a perfect match, it is possible to win. But if we make one mistake in this tournament, you say 'bye bye'," he said.
"We are very happy with our tournament until now and I think the Iraqi people are very proud of the players and their performance," added Casas, a former assistant to Luis Enrique in Spain's national team.
"But tomorrow we have a very, very, very hard match against a very, very good team.
"In any match, all is possible -- one red card, one penalty, one mistake, nervousness, so we aren't favourites."
A Jordan victory would however be a shock.
In contrast to Iraq's three wins from three in the group stage, Jordan won one match and reached the knockout rounds as one of the four best third-placed sides.
Casas is wary of Jordan's attackers but won't change his philosophy, his Iraq team having scored eight goals so far.
"Our style is clear -- we try to be offensive, have the ball under control, make a lot of chances," said Casas.
"We don't change our style."
At the pre-match press conference, the 50-year-old was irked by a question about interviews he has given to Spanish media during the tournament, calling any criticism "a big stupid".
