Having won all three matches to top Group C, Iran will start the last-eight fixture as favourites against the 2007 champions.
Iraq's only defeat in the group stages came in a plucky 1-0 loss to favourites Japan, though, and Iran coach Queiroz is well aware of the quality possessed by their opponents.
However, the Portuguese believes his team - who last won the Asian Cup in 1976 - can triumph if they remain focused throughout.
"We know that in a quarter-final there aren't favourites, your value is what you do in the game and Iraq showed against Japan the result of their preparation and investment," he said.
"The Iraqi players are comfortable with the ball and comfortable in the defensive backline so we know we will face a very difficult team to beat.
"I said to my boys this morning 'everything to win, nothing to lose'. The main thing, the most important thing is to be focused and concentrated in our duties and our tasks."
Queiroz also praised the Iran fans for their vocal support during the tournament and the former Real Madrid coach stated the team is extra determined to repay their backing.
"No doubt that the reason why we're here is very simple, we play for them," he added. "That's the only reason why we play the game, we play for the fans.
"The fans have created a nice environment around the stadiums and it is always great motivation for the players and there is no doubt that in these kind of games any help is welcome.
"But also it increases our responsibility and we take it as a challenge for us. To fulfil the expectations and support they give us with a good performance and good result."
