The Irish side begin the first qualifying round tie as favourites after punching above their weight with back-to-back FAI Cup and League Cup triumphs in the last two years.
Manager Alan Mathews has overseen all that success and believes they have the ability to rise to the occasion again.
"If I knew why we're so good in knockout football I would bottle it and use it every week. It's the $64,000 question.
"When I came from Shelbourne, I tried to bring an element of professionalism to the part-time set-up at Longford.
"The players I've brought in have adapted to that well. They realise it's going to be difficult for them to win the league because over 36 weeks a full-time set-up is going to have the advantage, but in a one-off anybody can beat anybody."
Longford have brought in former Cardiff goalkeeper Seamus Kelly in on loan from Bohemians after regular back-up Michael Dempsey broke an ankle in the League Cup outing against Cork.