Warren Gatland's side haven't won a Test in Australia in 43 years but the Scarlets playmaker is plotting to put an end to that barren run in the three-match series Down Under in June.
The most recent success against the Wallabies came in November 2008, but with Wales now riding the crest of a wave Priestland admits it's now or never.
"There is added pressure now because every time we go on the field, people expect us to win," he said.
"The nation wants a southern hemisphere scalp as well and, hopefully, we can get one before the autumn.
"As a squad we want a southern hemisphere scalp. We know what to expect because they have world class players and some of the most skilful players in world rugby.
"Any time you play against them, you have to be at your best otherwise they will cut you to pieces.
"We have an opportunity going down there, it will be tough. They have a few injuries and we have a few injuries so it's a good time to play them.
"You have to be at your best and hopefully we prepare well and give ourselves the best possible chance to get a southern hemisphere scalp."