Bilbao travel to the Vicente Calderon for the first leg later this week with Atletico boasting an unbeaten home record this season, but Iraola believes that the Basque outfit can cause an upset.
"We haven't been able to beat them in the Calderon lately. We want to do it this time. It's two legs and we need to score because we know how difficult it is to recover," he told reporters.
Bilbao have won nine of their 11 league fixtures on their own patch this season, remaining unbeaten in the process, but they have lost five times on their travels.