Osasuna won the first leg 1-0 but Poulsen believes Sevilla can break down the visitors' solid defence and make it through to the final.
"Osasuna come with a good result and will without doubt rely on counter attacks," the Dane told BT.
"It will be tough, Osasuna is not a typical Spanish side, they play on the result.
"But I still believe we can score the goals that are necessary."
